EISTING  MILK 

AND  ITS  PRODIJCTS 

FARRINQTON  and  WOLL 


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Dr.  S.   M.   BABCOCK, 

INVENTOR  OF  THE  BABCOCK  MILK  TEST. 


TESTING  MILK 

AND  ITS  PRODUCTS 


A  MANUAL  FOR  DAIRY  STUDENTS,  CREAMERY-  AND  CHEESE 

FACTORY  OPERATORS,  FOOD  CHEMISTS,  AND 

DAIRY  FARMERS 


BY 


E.  H.  FARRINGTON         and        F.  W.  WOLL 

Professor  in  Charge  of  Dairy  School  Asst.  Prof,  of  AgrH  Chemistry 

Of  the  University  of  Wisconsin 


"CIKitb  illustrations 


FOURTEENTH  REVISED  AND  ENLARGED  EDITION 


MADISON,  WIS. 

Mendota  Book  Company 

1904 

AIvI.   RIGHTS  RESERVED 


Copyright,  1897,  1899,  1901  akd  1904, 
By  E.  H.  FARRINGTON  and  F.  W.  WOLL. 


CANTWBLL  PBINTING   COMPANY 
MADISON,  WIS. 


PREFACE  TO  FIRST  EDITION. 


The  present  volume  is  intended  for  the  use  of  dairy  students, 
factory  operators,  dairymen,  food  chemists,  and  others  inter- 
ested in  the  testing  or  analysis  of  milk  and  its  products.  The 
subject  has  been  largely  treated  in  a  popular  manner;  accuracy 
and  clearness  of  statement,  and  systematic  arrangement  of  the 
subject  matter  have,  however,  been  constantly  kept  in  mind. 
The  aim  has  been  to  make  the  presentation  intelligible  to 
students  with  no  further  training  than  a  common-school  educa- 
tion, but  their  work  will  naturally  be  greatly  lightened  by  the 
aid  of  an  able  teacher. 

Complete  directions  for  making  tests  of  milk  and  other  dairy 
products  are  given;  difficulties  which  the  beginner  may  meet 
with  are  considered  in  detail,  and  suggestions  ofTered  for  avoid- 
ing them.  It  is  expected  that  a  factory  operator  or  practical 
dairyman,  by  exercising  common  sense  and  ordinary  care,  can 
obtain  sufficient  knowledge  of  the  subject  through  a  study  of 
the  various  chapters  of  this  book  to  make  tests  of  milk,  cream, 
etc.,  even  if  he  has  had  no  previous  experience  in  this  line. 

For  the  benefit  of  advanced  dairy  students  who  are  some- 
what familiar  with  chemistry  and  chemical  operations,  Chapter 
XIV  has  been  added  giving  detailed  instructions  for  the  com- 
plete chemical  analysis  of  milk  and  other  dairy  products.  The 
detection  of  preservatives  and  of  artificial  butter  or  filled  cheese 
has  also  been  treated  in  this  connection. 

As  the  subject  of  milk  testing  is  intimately  connected  with 
the  payment  for  the  milk  delivered  at  butter-  and  cheese  fac- 
tories, and  with  factory  dividends,  a  chapter  has  been  devoted 
to  a  discussion  of  the  various  systems  of  factory  book-keeping, 
and  tables  greatly  facilitating  the  work  of  the  factory  secretary 
or  bookkeeper  have  been  prepared  and  are  included  in  the 
Appendix. 


^1^ 


iv  Testing  Milk  and  Its  Products. 

Acknowledgment  is  due  to  the  following  parties  for  the  use 
of  electrotypes,  viz.:  Creamery  Pkg.  Mfg.  Co.,  Chicago,  111.; 
Vermont  Farm  Machine  Co.,  Bellows  Falls,  Vt.;  Elgin  Mfg. 
Co.,  Elgin,  111.;  D.  H.  Burrell  &  Co.,  Little  Falls,  N.  Y.;  De 
Laval  Separator  Co.,  New  York  City;  Henry  Tromuer,  Phila- 
delphia, Pa.;  Springer  Torsion  Balance  Co.,  New  York  City; 
J.  H.  Monrad,  Winnetka,  111.;  Borden  &  Selleck  Co.,  Chicago, 
111.;  Dairymen's  Supply  Co.,  Philadelphia,  Pa.;  Bausch  & 
Lomb  Opt.  Co.,  Rochester,  N.  Y.;  John  W.  Decker,  Columbus, 
Ohio;  C.  L.  Fitch,  Forth  Atkinson,  Wis.,  and  the  agricultural 
experiment  stations  at  New  Haven,  Conn.,  and  Madison,  Wis. 

Madison,  Wis.,  October  1,  1897. 


PREFACE  TO  THIRTEENTH  EDITION. 


The  first  three  editions  of  this  book  were  sold  in  about  a 
year  and  the  twelfth  edition  was  exhausted  six  years  later. 
Every  year  that  passes  brings  some  valuable  contributions  to 
our  knowledge  of  the  subjects  treated  in  the  book  and  a  fre- 
quent revision  of  it  is  therefore  desirable. 

The  present  edition  contains  all  the  methods  and  descrip- 
tions that  have  stood  the  test  of  actual  use  during  the  past  few 
years;  the  new  information  which  has  appeared  since  the 
last  revision  of  the  book,  has  been  carefully  sifted,  and  what 
was  deemed  of  sufficient  importance  has  been  incorporated  in 
such  detail  as  the  scope  of  the  book  permitted;  many  changes 
and  additions  suggested  by  the  experience  of  the  authors  have 
also  been  introduced.  In  brief,  the  book  has  been  subjected  to 
a  renewed,  critical  examination  and  revision.  The  general 
adoption  of  it  as  a  text  book  in  American  Dairy  Schools,  as  well 
as  the  favorable  reception  which  it  .has  been  accorded  by  users 
of  Babcock  testers,  and  the  dairy  public  in  general,  is  naturally 
a  source  of  gratification  to  the  authors. 

Madison,  Wis.,  March  25,  1904. 


TABLE  OF  CONTENTS. 


Page. 
Introduction 1 

Chap.  I.    Composition  of  milk  and  its  products  .    .        11 

Composition  of  milk:  Water.  Fat.  Casein  and  albu- 
men. Milk  sugar  (lactose).  Ash.  Other  components. 
Colostrum  milk.     Composition  of  milk  products. 

Chap.  II.    Sampling  milk 23 

Sweet   milk.     Partially    churned    milk.     Sour  milk. 
Frozen  milk. 
Chap.  III.    The  Babcock  test  — Milk 28 

A.  Directions  for  making  the  test: 

Sampling.  Adding  acid.  Mixing  milk  and  acid. 
Whirling  bottles.  Adding  water.  Measuring  the  fat. 
Lutley  dividers. 

B.  Discussion  of  the  details  of  the  test  : 

1.  Glassware.  Test  bottles.  Pipettes.  "  Fool  pipettes. " 
Acid  measures.  The  Swedish  acid  bottle.  Calibration  of 
glassware.  Calibration  with  mercury.  Calibration  with 
water.     The  Trowbridge  method  of  calibration. 

2.  Centrifugal  machines.  Speed  required  for  the  com- 
plete separation  of  the  fat.  Ascertaining  the  necessary 
speed  of  testers.     Hand  testers.     Power  testers. 

3.  Sulfuric  acid.  Testing  the  strength  of  the  acid.  The 
Swedish  acid  tester.  The  color  of  the  fat  column  an  index 
to  the  strength  of  the  acid  used.  Influence  of  temperature 
on  the  separation  of  fat. 

4.  Water  to  be  used  in  the  Babcock  test.  Reservoir  for 
water. 

5.  Modificationsofthe  Babcock  test.  The  Russian  milk 
test.  Bartlett's  modification.  Siegfeld's  modification. 
Bausch  and  Lomb  centrifuge. 

Chap.  IV.    The  Babcock  test  — Cream 74 

Errors  of  measuring  the  cream.  Weighing  cream. 
Cream- test  bottles.  The  bulb-necked  cream  bottle.  The 
Winton  cream  bottle.  Cream-weighing  scales.  Measur- 
ing cream  for  testing.  Use  of  milk  test  bottle.  Use  of 
5  CO  pipette.     Proper  readings  of  cream  tests. 


vi  Testing  Milk  and  Its  Products. 

Page. 
Chap.  V.     The    Babcock     test  — other     milk    pro- 
ducts              85 

Skim  milk,  butter  milk  and  whey.   The  double-necked 
test  bottle.     The  Wagner  test  bottle.    The  double-sized 
skim  milk  bottle.    Cheese.     Condensed  milk. 
Chap  VI.    The  lactometer  and  its  application    .    .        93 

The  Quevenne  lactometer.  Influence  of  temperature. 
N.  Y.  Board  of  Health  lactometer.  Reading  the  lacto- 
meter. Time  of  taking  lactometer  readings.  Influence  of 
bi-chromate  on  lactometer  reading.  Calculation  of  milk 
solids.  Adulteration  of  milk.  Legal  standards.  The 
specific  gravity  of  the  milk  solids.  Calculation  of  extent 
of  adulteration:  Skimming.  Watering.  Watering  and 
skimming. 
Chap  VII.    Testing  the  acidity  of  milk  and  cream      108 

Cause  of  acidity  in  milk.  Methods  of  testing  acidity. 
Manns'  test.  Devarda's  acidimeter.  The  alkaline-tablet 
test.  Determination  of  acidity  in  sour  cream.  Spillman's 
cylinder.  Rapid  estimation  of  the  aciditj^  of  apparently 
sweet  milk  and  cream.  Detecting  boracic-acid  preserva- 
tives in  milk.  "Alkaline  Tabs." 
Chap.  VIII.    Testing  the  purity  of  milk 125 

The  Wisconsin  curd  test.    The  fermentation  test.   The 
Monrad  rennet  test.     The  Marschall  rennet  test. 
Chap.  IX.    Testing  milk  on  the  farm 131 

Variations  in  milk  of  single  cows.  Number  of  tests  re- 
quired during  a  period  of  lactation  in  testing  cows.  When 
to  test  a  cow.  Gurler's  method.  Sampling  milk  of  single 
cows.  Variations  in  herd  milk.  Influence  of  heavy  grain 
feeding  on  the  quality  of  milk.  Influence  of  pasture  on 
the  quality  of  milk.  Method  of  improving  the  quality  of 
milk. 
Chap.  X.    Composite  samples  of  milk 148 

Methods  of  taking  composite  samples.  Use  of  tin 
dipper.  Drip  sample.  Scovell  sampling  tube.  The 
equity  milk  sampler.  One-third  sample  pipette.  Pre- 
servatives for  composite  samples.  Care  of  composite 
samples.  Fallacy  of  averaging  percentages.  A  patron's 
dilemma. 


Table  of  Contents.  vii 

Page. 

Chap.  XI.    Cream  testing  at  creameries 165 

The  space  system.  The  oil-test  churn.  The  Babcock 
test  for  cream.     Sampling  and  weighing. 

Chap.  XII.    Ca  lculation  of  butter  and  cheese  yields      176 

A.  Calculation  of  yield  of  butter:  Butter  fat  test  and 
yield  of  butter.  Variations  in  composition  of  butter. 
Overrun  of  churn  over  test.  Factors  influencing  the 
overrun.  Calculation  of  overrun.  Conversion  factor  for 
butter  fat.  Butter  yield  from  milk  of  different  richness. 
Use  of  butter  chart.     Use  of  overrun  table. 

B.  Calculation  of  yield  of  cheese:  From  fat.  From 
solids  not  fat  and  fat.     From  casein  and  fat. 

Chap.  XIII.    Calculating  dividends 190 

A.  Calculating  dividends  at  creameries:  Proprietary 
creameries.  Co-operative  creameries.  Illustrations  of 
calculations  of  dividends.  Paying  for  butter  delivered. 
Milk  and  cream  dividends.     Relative-value  tables. 

B.  Calculating  dividends  at  cheese  factories:  Proprie- 
tary factories.     Co-operative  factories. 

Chap.  XIV.  Chemical  analysis  of  milk  and  its  pro- 
ducts   204 

Milk.  Cream.  Skim  milk,  butter  milk,  whey.  Con- 
densed milk.  Butter.  A  practical  method  of  estimat- 
ing salt  in  butter.  Detection  of  artificial  butter.  Reich- 
ert-Wollny  method  (Volatile  acids).  Tests  for  the  detec- 
tion of  oleomargarine  and  renovated  butter.  The  boiling 
test.  The  Waterhouse  test.  Cheese.  Detection  of  oleo- 
margarine cheese  ("Filled"  cheese). 

Tests  for  adulteration  of  milk  and  cream.  Detection 
of  pasteurized  milk  or  cream.  Boiled  milk.  Detection 
of  preservatives  in  dairy  products.  Boracic  acid.  Bi-car- 
bonate  of  soda.  Fluorids.  Salicylic  acid.  Formalde- 
hyde.   Government  food  standards. 

Appendix 233 

Table       I.     Composition  of  milk  and  its  products. 
Table     II.     State  and  city  standards  for  dairy  products. 
Table  III.     Quevenne  lactometer  degrees  correspond- 
ing to  the  scale  of  the  N.  Y.  Board  of  Health  lactometers. 


viii  Testing  Milk  and  Its  Products. 

Page. 

Table  IV.  Value  of  — ^^^^ —  for  specific  gravities  from 
1.019  to  1.0369. 

Table  V.     Correction  table  for  specific  gravity  of  milk. 

Table  VI.  Per  cent,  of  solids  not  fat,  corresponding  to 
0  to  6  per  cent,  of  fat  and  lactometer  readings  of  26  to  36. 

Directions  for  the  use  of  tables  VII,  VIII,  IX  and  XI. 

Table  VII.  Pounds  of  fat  in  1  to  10,000  pounds  of  milk 
testing  3  to  5.35  per  cent. 

Table  VIII.  Pounds  of  fat  in  1  to  1,000  lbs.  of  cream 
testing  12.0  to  50.0  per  cent.  fat. 

Table  IX.  Amount  due  for  butter  fat,  in  dollars  and 
cents,  at  12  to  25  cents  per  pound. 

Table  X.     Relative- value  tables. 

Table  XI.  Butter  chart,  showing  calculated  yield  of 
butter,  in  pounds,  from  1  to  10,000  pounds  of  milk  testing 
3.0  to  5.3  per  cent,  of  fat. 

Table  XII.  Overrun  table,  showing  pounds  of  butter 
from  100  pounds  of  milk. 

Table  XIII.  Yield  of  cheese,  corresponding  to  2.5  to  6 
per  cent,  of  fat,  with  lactometer  readings  of  26  to  36. 

Table  XIV.  Comparisons  of  Fahrenheit  and  Centi- 
grade (Celcius)  thermometer  scales. 

Table  XV.  Comparison  of  metric  and  customary 
weights  and  measures. 

Suggestions  regarding  the  organization  of  co-operative 
creameries  and  cheese  factories. 

Constitution  and  by-laws  for  co-operative  factory  asso- 
ciations. 

Index 264 


Testing  Milk  and  its  Products^ 


INTRODUCTION. 

The  need  of  a  rapid,  accurate  and  inexpensive  method 
of  determining  the  amount  of  butter  fat  in  milk  and  other 
dairy  products  became  more  and  more  apparent,  in  this 
country  and  abroad,  with  the  progress  of  the  dairy  in- 
dustry, and  especially  with  the  growth  of  the  factory 
system  of  butter-  and  cheese  making  during  the  last  few 
decades.  So  long  as  each  farmer  made  his  own  butter 
and  sold  it  to  private  customers  or  at  the  village  grocery, 
it  was  not  a  matter  of  much  importance  to  others  whether 
the  milk  produced  by  his  cows  was  rich  or  poor.  But 
as  creameries  and  cheese  factories  multiplied,  and  farm- 
ers in  the  dairy  sections  of  our  country  became  to  a 
large  extent  patrons  of  one  or  the  other  of  these,  a  sys- 
tem of  equitable  payment  for  the  milk  or  cream  delivered 
became  a  vital  question. 

I.  The  creameries  in  existence  in  this  country  up  to 
within  fifteen  years  were  nearly  all  conducted  on  the 
cream-gathering  plan:  the  different  patrons  creamed 
their  milk  by  the  gravity  process,  and  the  cream  was 
hauled  to  the  creamery,  usually  twice  or  three  times  a 
week,  where  it  was  then  ripened  and  churned.  The 
patrons  were  paid  per  inch  of  cream  furnished;  a  creamery 
inch  is  a  quantity  of  cream  which  fills  a  can  twelve  inches 
1 

fUffmuMM^ 


2  Testing  Milk  and  Its  Products. 

in  diameter,  one  inch  high,  or  113  cubic  inches.  This 
quantity  of  cream  was  supposed  to  make  a  pound  of  but- 
ter, but  cream  from  dijGferent  sources,  or  even  from  the 
same  sources  at  different  times,  varies  greatly  in  butter- 
producing  capacity,  as  will  be  shown  under  the  subject 
of  cream  testing  (210^).  The  system  of  paying  for  the 
number  of  creamery  inches  delivered  could  not  therefore 
long  give  satisfaction. 

The  proposition  to  take  out  a  small  portion,  a  pint  or 
half  a  pint,  of  the  cream  furnished  by  each  patron,  and 
determine  the  amount  of  butter  which  these  samples 
would  make  on  being  churned  in  so-called  test  churns, 
found  but  a  very  limited  acceptance,  on  account  of  the 
labor  involved  and  the  difficulty  of  producing  a  first- class 
article  from  all  the  small  batches  of  butter  thus  obtained. 

2.  The  introduction  of  the  so-called  oil  test  churn  in 
creameries  which  followed  the  creamery- inch  system, 
marked  a  decided  step  in  advance,  and  it  soon  came  into 
general  use  in  gathered- cream  factories  (203).  In  this 
test,  glass  tubes  of  about  f  inch  internal  diameter  and 
nine  inches  long,  are  filled  with  cream  to  a  depth  of  five 
inches,  and  the  cream  is  churned;  the  tubes  are  then  placed 
in  hot  water,  and  the  column  of  melted  butter  formed  at 
the  top  is  read  off  by  means  of  a  scale  showing  the  num- 
ber of  pounds  of  butter  per  creamery  inch  corresponding 
to  different  depths  of  melted  butter.  While  the  oil  test 
is  capable  of  showing  the  difference  between  good  and 
poor  cream,  it  can  not  make  strictly  accurate  distinctions 
between  different  grades  of  good  and  of  poor  cream.  ^  As 


Refers  to  paragraph  numbers. 
Wisconsin  experiment  station,  bulletin  12. 


Introduction.  3 

a  result,'  perfect  justice  cannot  be  done  to  different  pat- 
rons of  creameries  where  payments  for  cream  delivered 
are  made  on  the  basis  of  this  test. 

3.  In  cheese  factories,  and  since  the  introduction  of  the 
centrifugal  cream  separator,  in  separator  creameries,  the 
problem  of  just  payment  for  the  milk  furnished  by  differ- 
ent patrons  was  no  less  perplexing  than  in  the  case  of 
gathered- cream  factories.  By  the  pooling  system  gener- 
ally adopted,  each  patron  received  payment  in  propor- 
tion to  the  number  of  pounds  of  milk  delivered,  irre- 
spective of  its  qualify.  Patrons  delivering  rich  milk 
naturally  will  not  be  satisfied  with  this  system  when  they 
find  that  their  milk  is  richer  than  that  of  their  neigh- 
boi's.  The  temptation  to  fraudulently  increase  the 
amount  of  milk  delivered,  by  watering,  or  to  lower  its 
quality  by  skimming,  will  furthermore  prove  too  strong 
for  some  patrons;  the  fact  that  it  was  difficult  to  prove 
any  fraud  committed,  from  lack  of  a  reliable  and  practi- 
cal method  of  milk  analysis,  rendered  this  pooling  system 
still  more  objectionable. 

4.  As  another  instance  in  which  the  need  of  a  simple 
test  for  determining  the  fat  content  of  different  kinds  of 
milk  was  strongly  felt,  may  be  mentioned  the  case  of  pri- 
vate dairymen  and  breeders  of  dairy  cattle  who  desired 
to  ascertain  the  butter-producing  capacities  of  the  indi- 
vidual cows  in  their  herds.  The  only  manner  in  which 
this  could  be  done,  was  by  the  cumbersome  method  of 
trial  churnings:  by  saving  the  milk  of  the  cow  to  be 
tested,  for  a  day  or  a  week,  and  churning  separately  the 
cream  obtained.  This  requires  a  large  amount  of  work 
when  a  number  of  cows  are  to  be  tested,  and  can  not 


4  Testing  Milk  and  Its  Products. 

therefore  be  done  except  in  comparatively  few  cases, 
with  cows  of  great  excellence  or  by  farmers  having  abun- 
dant hired  help. 

5.  Introduction  of  milk  tests.  The  first  method  which 
fulfilled  all  reasonable  demands  of  a  practical  and  reli- 
able milk  and  cream  test  was  the Babcock  test,  invented  by 
Dr.  S.  M.  Babcock,  chief  chemist  to  the  Wisconsin  experi- 
ment station.  A  description  of  the  test  was  first  pub- 
lished in  July,  1890,  as  bulletin  'No.  24  of  Wisconsin  ex- 
periment station,  entitled :  A  new  method  for  the  estimation 
of  fat  in  milk,  especia'ly  adapted  to  creameries  and  cheese 
factories.  This  test,  which  is  now  known  and  adopted  in 
all  parts  of  the  world  where  dairying  is  an  important  in- 
dustry, was  not,  however,  the  first  method  proposed  for 
this  purpose  which  could  be  successfully  operated  out- 
side of  chemical  laboratories.  It  was  preceded  by  a 
number  of  different  methods,  the  first  one  published  in 
this  country  being  Short's  method,  invented  by  Mr.  F. 
G.  Short  and  described  in  bulletin  Xo.  16  of  Wisconsin 
experiment  station  (July,  1888). 

6.  Short's  test.  Iq  this  ingenious  method,  a  certain 
quantity  of  milk  (20  cc.  ^ )  was  boiled  with  an  alkali  solu- 
tion and  afterwards  with  a  mixture  of  sulfuric  and  acetic 
acids;  a  layer  of  insoluble  fatty  acids  separated  on  top 
of  the  liquid  and  was  brought  into  the  graduated  neck 
of  the  test  bottles  by  addition  of  hot  water;  the  reading 
gave  the  per  cent,  of  fat  in  the  sample  of  milk  tested. 

Short's  method  did  not  find  very  wide  application, 
both  because  it  was  rather  lengthy  and  its  manipulations 
somewhat  difficult  for  non-chemists,  and  because  several 

'  See  48,  footnote. 


Introduction, 


tion;  the  speed  of  the  tester,  the  strength  of  the  acid,  the 
temperature  of  the  milk  to  be  tested,  and  other  points, 
always  require  watching,  lest  the  results  obtained  be  too 
low  or  otherwise  unsatisfactory.  In  the  hands  of  careful 
operators  the  test  can,  however,  always  be  relied  upon 
to  give  most  satisfactory  results. 

10.  Foreign  Methods.  In  European  countries  four 
practical  milk  and  cream  tests,  besides  the  Babcock  test, 
are  in  use  at  the  present  time,  viz.:  Gerber^s  acid- 
hutyrometer,  the  lactocrite,DeLavaVs  butyrometer,and  Fjord'' 8 
certrifugal  cream  test.  ^ 

Of  these  the  last  test 
given  has  never,  to  our 
knowledge,  been  intro- 
duced into  this  country, 
and  the  first  three  only  on 
a  small  scale. 

11.  The  Gerber  method' 
(fig.  1)  is  essentially  the 
old  Beimling  method  (7), 
worked  out  independently 
by  the  Swiss  chemist.  Dr. 
]Sr.  Gerber.  In  this  test 
sulfuric  acid  of  the  same 
strength  is  used  as  in  the 
Babcock  test,  and  a  small 
quantity  of  amyl  alcohol  is  added, 
facilitates  the   separation    of  the 


Fig.  1.    The  Gerber  acid- 
butyrometer. 


The  amyl  alcohol 
fat,    but  introduces 


1  The  Lister-Babcock  milk  test  advertised  in  English  papers  and  known 
as  such  in  England,  is  the  regular  Babcock  test,  to  which  the  English  man- 
ufacturers have  prefixed  their  names;  the  same  applies  to  the  ^/li&orn- 
Babcock  method  and  the  Krugmann-Babcock  method. 

2  Gerber,  Die  praktische  Milchprufung,  7th  edition,  1900. 


8 


Testing  MilJ:  and  Its  Products. 


a  source  of  error  which  may  become  serious,  when  the 
results  obtained  with  a  new  lot  of  amyl  alcohol  can  not 
be  checked  against  gravimetric  analysis  or  against 
tests  made  with  amyl  alcohol  known  to  give  correct 
results.  This  method  is,  however,  extensively  used 
in  Euroi)ean  countries,  having  there  practically  re- 
placed the  Babcock  test  or  been  adopted  in  preference 
to  it. 

12.  The  Lactocrite  was  one  of  the  earliest  practical 
milk  tests  introduced.  It  was  invented  by  De  Laval  in 
1886.  The  acids  used  in  this  test  are  lactic  acid  (origi- 
nally, acetic  acid)  with  a  mixture  of  hydrochloric  and 
sulfuric  acids.     This  test  is  now  but  rarely  met  with. 

13.  In  the  De  Laval  butyrometer  (fig.  2)  the  same  acid 
is  used  as  in  the  Babcock  test,  but  the  tubes  employed  and 
the  manipulations  of  the  method  differ  materially  from 


Fig.  2.    De  Laval's  butyrometer. 


Introduction. 


this  test;  a  smaller  sample  of  milk  is  taken  (only  2  cc. ) 
and  a  correspondingly  small  quantity  of  acid  used.  Where 
a  large  number  of  milk  samples  are  tested  every  day, 
as  is  the  case,  for  instance,  in  European  milk  control  sta- 
tions, the  butyrometer  may  be  preferable  to  the  Babcock 
test;  but  it  requires  more  skill  of  the  operator  and  does 
not  work  satisfactorily  in  case  of  sour,  loppered,  or 
partially  churned  milk.  The  machine  placed  on  the 
market  both  by  Dr.  Gerber  and  the  De  Laval  Company 
are  more  expensive  than  the  Babcock  testers  sold  in  this 
country;  theDe  Laval  test  requires  a  high  speed,  5-6000 
revolutions  per  minute;  and  therefore  places  greater  de- 
mands for  solidity  in  the  machine  than  does  the  Babcock 
test. 

14.  Fjord's  centrifugal  cream  tester^  (fig.  3)  is  exten- 
sively used  in  Denmark  and  is  mentioned  in  this  connec- 
tion as  it  furnishes,  as  a 
rule,  a  reliable  method  for 
comparing  the  quality  of 
different  lots  of  milk.  The 
method  was  published  in 
1878, by  the  late  K  J.  Fjord, 
director  of  the  state  experi- 
ment station  in  Copenhagen, 
through  whose  exertions 
and  on  whose  authority  it 
was  introduced  into  Danish  creameries  in  the  middle  of 
the  eighties.  No  chemicals  are  added  in  this  test,  the  milk 
being  simply  placed  in  glass  tubes,  seven  inches  long 
and  about  two- thirds  of  an  inch  in  diameter,  and  whirled 


Fig,  3. 


Fjord's  centrifugal' oream 
tester. 


1  State  Danish  experiment  station,  Copenhagen,  sixth  and  ninth  re- 
ports, 1885-7. 


10  Testing  Milk  and  Its  Products. 

for  twenty  minutes  at  a  rate  of  2000  revolutions  per 
minute  at  55°  C  (131°  F. ).  The  reading  of  the  cream 
layer  thus  obtained  gives  the  per  cent,  of  cream,  and 
not  of  butter  fat,  in  the  sample  tested.  One  hundred 
and  nine-two  samples  of  milk  can  be  tested  simultan- 
eously. Within  the  limits  of  normal  Danish  herd  milk, 
the  results  obtained  correspond  to  the  percents  of  fat 
present  in  the  samples,  one  per  cent,  of  cream  being 
equal  to  about  0.7  per  cent,  of  fat;  outside  of  these  limits 
the  test  is,  however,  unreliable,  especially  in  case  of 
very  rich  milk  and  strippers'  milk.  Only  sweet  milk 
can  be  tested  by  this  method.  The  recent  introduction 
of  milk  tests  proper  into  Denmark,  like  the  Gerber,  Bab- 
cock  and  De  Laval  tests  may,  however,  in  time  force  the 
Fjord  cream  test  out  of  Danish  creameries,  for  similar 
reasons  that  relegated  to  obscurity  the  gravity  cream 
tests.  1 


1  Among  foreign  milk  tests  in  use  abroad  should  also  be  mentioned  the 
Wollny  Iiefractomet(fr,wh\ch,  in  the  hands  of  a  trained  chemist,  may  prove 
better  adapted  for  use  where  a  very  large  number  of  samples  are  to  be 
tested  at  a  time,  than  any  other  milk  test  available. 


CHAPTER  I. 

COMPOSITION  OP  MILK  AND  ITS  PRODUCTS. 

Before  taking  up  the  discussion  of  the  Babcock  milk 
^  test,  a  brief  description  of  the  chemistry  of  milk  and  its 
products  is  given,  so  that  the  student  may  understand 
what  are  the  components  of  dairy  products,  and  the  rela- 
tion of  these  to  each  other.  Only  such  points  as  have  a 
direct  bearing  on  the  subject  of  milk  testing  and  the  use 
of  milk  tests  in  butter  and  cheese  factories  or  private 
dairies  will  be  treated  in  this  chapter,  and  the  reader  is 
referred  to  standard  works  on  dairying  for  more  detailed 
information  in  regard  to  the  composition  of  dairy  pro- 
ducts. 

15.  Composition  of  Milk.  Milk  is  composed  of  the  fol- 
lowing substances:  water,  fat,  casein,  albumen,  milk  sugar, 
and  ash.  A  few  other  substances  are  present  in  small 
quantities,  but  they  are  hardly  of  any  practical  impor- 
tance and  will  not  be  considered  here.  The  components 
of  the  milk  less  the  water  are  known  collectively  as  milk 
solids  or  total  solids,  and  the  total  solids  less  the  fat,  i.  e. , 
casein,  albumen,  milk  sugar,  and  ash,  are  often  spoken 
of  as  solids  not  fat  or  the  non-fatty  milk  solids.  The  milk 
serum  includes  all  components  of  the  milk  less  the  fat; 
the  serum  solids  are  therefore  another  name  for  the  solids 
not  fat;  when  given,  they  are,  however,  generally  calcu- 
lated to  per  cent,  of  milk  serum,  not  of  milk.  If,  e.  g., 
a  sample  of  milk  contains  nine  per  cent,  of  solids  not  fat, 


12  Testing  Milk  and  Its  Products. 

and  three  per  cent,  of  fat,  the  milk  serum  will  make  up 
97"per  cent,  of  the  milk,  and  the  serum  solids,  '^-\\^^  = 
9.28  per  cent,  of  the  milk  serum. 

16.  Water.  The  amount  of  water  contained  in  cows' 
milk  ranges  from  82  to  90  per  cent.  Normal  cows'  milk 
will  not, as  a  rule, contain  more  than  88  percent,  of  water, 
nor  less  than  84  per  cent.  In  states  where  there  are  laws 
regulating  the  sale  of  milk,  as  is  the  case  in  eighteen  states 
in  the  union  (see  A2)pendijc,Ta,h\ell),  the  maximum  limit 
for  water  in  milk  in  all  instances  but  one  (South  Carolina) 
is  88  per  cent. ;  the  state  mentioned  allows  88.5  per  cent, 
of  water  in  milk  offered  for  sale  within  her  borders.  The 
effect  of  fraudulently  increasing  the  water  content  of 
milk  by  watering  is  considered  under  Adulteration  of 
Milk  (118). 

17.  Fat.  The  fat  in  milk  is  not  in  solution,  but  sus- 
pended as  very  minute  globules,  which  form  an  emulsion 
with  the  milk  serum;  the  globules  are  present  in  immense 
numbers,  viz.,  on  the  average  about  one  hundred  millions 
in  a  single  drop  of  milk;  a  quart  of  milk  will  contain 
about  two  thousand  billions  of  fat  globules,  a  number 
written  with  thirteen  figures.  The  size  of  the  globules 
in  the  milk  from  the  same  cows  varies  according  to  the 
stage  of  the  period  of  lactation,  the  globules  being  largest 
at  the  beginning  of  the  lactation  period,  and  gradually 
decreasing  in  size  with  its  progress.  Different  breeds  of 
cows  have  fat  globules  of  different  average  sizes;  the 
Channel  Island  cows  are  thus  noted  for  the  relatively 
large  fat  globules  of  their  milk,  while  the  lowland 
breeds,  the  Ayrshire,  and  other  breeds  have  uniformly 
smaller  globules.     The    diameter    of  average  sized  fat 


Composition  of  Mill-  and  Its  Products.  13 

globules  in  fresh  milkers  is  about  0.004  millimeter,  or 
one  six- thousandth  of  an  inch;  that  is,  it  takes  about  six 
thousand  such  globules  placed  side  by  side  to  cover  one 
inch  in  length.  The  globules  in  any  sample  of  milk 
vary  greatly  in  size;  the  largest  globules  are  recovered 
in  the  cream  when  the  milk  is  set  or  run  through  a  cream 
separator,  and  the  smallest  ones  remain  in  the  skim  milk; 
thoroughly  skimmed  separator  skim  milk  contains  only 
a  relatively  small  number  of  very  minute  fat  globules. 

Milk  fat  is  composed  of  so-called  glycerides  of  the  fatty 
acids,  i.  e.,  compounds  of  the  latter  with  glycerin;  some 
of  the  fatty  acids  are  insoluble  in  water,  viz.,  palmitic, 
stearic,  and  oleic  acids,  while  others  are  soluble  and  vol- 
atile, the  chief  ones  among  the  latter  being  butyric,  cap- 
rylic,and  capronic  acids.  The  glycerides  of  the  insoluble 
fatty  acids  make  up  about  92  per  cent,  of  the  pure  milk 
fat;  about  8  per  cent,  of  the  glycerides  of  volatile  fatty 
acids  are  therefore  found  in  natural  milk- (and  butter-) 
fat.  The  distinction  between  natural  and  artificial  but- 
ter lies  mainly  in  this  point,  since  artificial  butter  (but- 
terine,  oleomargarine)  as  well  as  other  solid  animal  fats 
contain  only  a  very  small  quantity  of  volatile  fatty  acids. 
The  glycerides  of  the  volatile  fatty  acids  are  unstable 
compounds,  easily  decomposed  through  the  action  of 
bacteria  or  light;  the  volatile  fatty  acids  thus  set  free, 
principally  butyric  acid,  are  the  cause  of  the  unpleasant 
odor  met  with  in  rancid  butter. 

Cows'  milk  generally  contains  between  three  and  six 
per  cent,  of  fat;  in  Americaa  milk  we  find,  on  the 
average,  toward  four  per  cent,  of  fat.  The  milk  from 
single  cows  in  perfect  health  will  occasionally  go  below 


14  Testing  Milk  and  Its  Products. 

or  above  the  limits  given,  but  the  mixed  milk  from  a 
whole  herd  rarely  falls  outside  of  these  limits.  The 
standard  adopted  by  the  U.  S.  government  for  fat  in  milk 
is  3.25  per  ct.  The  legal  standard  for  fat  in  milk  in  most 
states  of  the  Union  is  3  per  cent. ;  Ehode  Island  allows 
milk  containing  2.5  per  cent,  of  fat  to  be  sold  as  pure, 
while  Georgia  and  Minnesota  require  it  to  contain  3.5  per 
cent.,  and  Massachussetts  3.7  per  cent,  (in  the  months  of 
May  and  June;  see  Appendix,  Table  II). 

18.  Casein  and  albumen.  These  belong  to  the  so-called 
nitrogenous  substances,  distinguished  from  the  other  com- 
ponents of  the  milk  by  the  fact  that  they  contain  the 
element  nitrogen.  Another  name  is  albuminoids  or  protein 
compounds.  Casein  is  precipitated,  by  rennet  in  the 
presence  of  soluble  calcium  salts,  and  by  dilute  acids  and 
certain  chemicals;  albumen  is  not  acted  upon  by  these 
agents,  but  is  coagulated  by  heat,  a  temperature  of  170°  F. 
being  sufficient  to  effect  a  perfect  coagulation.  The 
casein,  with  fat  and  water,  form  the  main  components  of 
nearly  all  kinds  of  cheese.  In  the  manufacture  of  Ched- 
dar and  most  other  solid  cheeses,  the  casein  is  coagulated 
by  rennet,  and  the  curd  thus  formed  holds  fat  and  whey 
mechanically,  the  latter  containing  in  solution  small 
quantities  of  non-fatty  milk  solids.  The  albumen  goes  into 
the  whey  and  is  lost  for  cheese  making;  in  some  countries 
it  is  also  made  into  cheese  by  evaporating  the  whey  under 
constant  stirring;  whole  milk  of  cows  or  goats  is  often  ad- 
ded and  incorporated  into  such  cheese  (primost,  gjedost). 

Casein  is  present  in  milk  partly  in  solution,  in  the 
same  way  as  milk  sugar,  soluble  ash-materials  and  albu- 
men, and  partly  in  suspension,  in  an  extremely  fine  col- 
loidal  condition,    mixed    or   combined    with   insoluble 


Composition  of  Milk  and  Its  Products.  15 

calcium  phosphates.  The  casein  and  calcium  phosphates 
in  suspension  in  milk  may  be  retained  on  a  filter  made 
of  porous  clay  (so-called  Chamherland  filters) . 

About  80  per  cent,  of  the  nitrogenous  compounds  of 
normal  cows'  milk  are  made  up  of  casein  j   the   rest  is 
largely  albumen.      If  the  amount  of  casein  in  milk  be 
determined  by  precipitation  with  rennet  or  dilute  acids, 
and  the  albumen  by  boiling  the  filtrate  from  the  casein 
precipitate,  it  will  be  found  that  the  sum  of  these  two 
compounds  does  not  make  up  the  total  quantity  of  nitro- 
genous constituents  in  the  milk.     The  small  remaining 
portion  (about  five  per   cent,  of  the  total  nitrogenous 
constituents)  has  been  called  by  various  authors,  globu- 
lin, albumose,  hemi-albumose,  nuclein,  nucleon,  proteose, 
etc.     The  nitrogenous  constituents  of  milk  are  very  un- 
stable compounds,  and  their  study  presents  many  and 
great  difiacultiesj  as  a  result  we  find  that  no  two  scien- 
tists who  have  made  a  special  study  of  these  compounds 
agree  as  to  their  properties,  aside  from  those  of  casein 
and  albumen,  or  their  relation  to  the   nitrogenous  sub- 
stances found  elsewhere  in  the  animal  body.      For  our 
purpose  we  may,  however,  consider  the  nitrogen  com- 
pounds of  milk  as  made  up  of  casein  and  albumen,  and 
the  term  casein  and  albumen,  as  used  in   this  book,   is 
meant  to  include  the   total  nitrogenous  constituents  of 
milk,  obtained  by  multiplying  the  total  nitrogen  content 
of  the  milk  by  6.25.^ 

1  The  factor  6.25  is  generally  used  for  obtaining  the  casein  and  albumen 
from  the  total  nitrogen  in  the  milk,  although  637  would  be  more  correct, 
since  tfiese  substances,  according  to  our  best  authorities,  contain  on  the 
average  15.7  percent,  of  nitrogen  ('i^  — g  37^ 


16  Testing  Milk  and  Its  Products. 

The  quantity  of  casein  in  normal  cows'  milk  will  vary 
from  2  to  4  percent,  and  of  albumen,  from  .5  to  .8  per 
cent.  The  total  content  of  casein  and  albumen  ranges 
between  2.5  and  4.6  per  cent.,  the  average  being  about 
3.2  per  cent.  Milk  with  a  low  fat  content  will  contain 
more  casein  and  albumen  than  fat,  while  the  reverse  is 
generally  true  in  case  of  milk  containing  more  than  3.5 
per  cent,  of  fat. 

19.  Milk  sugar  or  lactose  belongs  to  the  group  of  organic 
compounds  known  as  carbohydrates.  It  is  a  commercial 
product  manufactured  from  whey  and  is  obtained  in  this 
process  as  pale  white  crystals,  of  less  sweet  taste  and  less 
soluble  in  water  than  ordinary  sugar  (cane  sugar,  sucrose). 
About  70  per  cent,  of  the  solids  in  the  whey,  and  33  per 
cent,  of  the  milk  solids,  are  composed  of  milk  sugar. 

When  milk  is  left  standing  for  some  time,  viz.,  from 
one  to  several  days,  according  to  the  temperature  of  the 
surrounding  medium,  it  will  turn  sour  and  soon  become 
thick  and  loppered.  This  change  in  the  composition 
and  the  appearance  of  the  milk  is  brought  about  through 
the  action  of  acid- forming  bacteria  on  the  milk  sugar. 
These  are  present  in  ordinary  milk  in  immense  numbers, 
and  under  favorable  conditions  of  temperature  multiply 
rapidly,  feeding  on  the  milk  sugar  as  they  grow,  and 
decomposing  it  into  lactic  acid.  When  this  change  alone 
occurs,  there  is  not  necessarily  a  loss  in  the  nutritive 
value  of  the  milk,  since  milk  sugar  breaks  up  directly  into 
lactic  acid,  as  shown  by  the  following  chemical  formula: 
Ci2H2  20ii.H.^O  (lactose)   =  4  CgHgOg   (lactic  acid). ^ 

1  One  molecule  of  milk  sugar  Is  composed  of  12  atoms  of  carbon  (C), 
22  atoms  of  hydrogen  (H),  11  atoms  of  oxygen  (O),  and  one  molecule  of 
water  (H  2  O).  In  the  same  way,  the  lactic-acid  molecule  consists  of  three 
atoms  of  carbon,  6  atoms  of  hydrogen,  and  3  atoms  of  oxygen. 


Composition  of  Milk  and  Its  Products.  17 

Ordinarily  the  souring  of  milk  is,  however,  more  com- 
plicated, and  other  organic  bodies,  like  butyric  acid,  al- 
cohol, etc.,  and  gases  like  carbonic  acid  are  formed,  re- 
sulting in  a  loss  in  the  feeding  value  of  the  milk.  While 
sour  milk  may  therefore  contain  a  somewhat  smaller  pro- 
portion of  food  elements  than  sweet  milk,  the  feeding  of 
it  to  farm  animals,  especially  pigs,  will  generally  pro- 
duce better  results  than  is  obtained  in  feeding  similar 
milk  in  a  sweet  condition.  The  cause  of  this  may  lie  in 
the  stimulating  effect  of  the  lactic  acid  of  sour  milk  on 
the  appetites  of  the  animals,  or  in  its  aiding  digestion  by 
increasing  the  acidity  of  the  stomach  juices. 

That  the  souring  of  milk  is  due  to  the  activities  of 
bacteria  present  therein  is  shown  clearly  by  the  fact  that 
sterile  milk,  i.  e.,  milk  in  which  all  germ  life  has  been 
killed,  will  remain  sweet  for  any  length  of  time  when 
kept  free  from  infection. 

The  amount  of  milk  sugar  found  in  normal  cows'  milk 
varies  from  3.5  to  6  per  cent.,  the  average  content  being 
about  5  per  cent. ;  in  sour  milk  this  content  is  decreased 
to  toward  4  per  cent. 

20.  Ash.  The  ash  or  mineral  substances  of  milk  are 
largely  composed  of  chlorids  and  phosphates  of  sodium, 
potassium,  magnesium  and  calcium;  iron  oxid  and  sul- 
furic and  citric  acids  are  also  present  in  small  quantities 
among  the  normal  mineral  milk  constituents.  The 
amounts  of  the  different  bases  and  acids  found  in  milk 
ash  have  been  determined  by  a  number  of  chemists;  the 
average  figures  obtained  are  given  in  the  following  table, 
calculated  per  100  parts  of  milk  (containing  .75  percent, 
of  ash)  and  per  100  parts  of  milk  ash. 


18  Testing  Milk  and  Its  Products. 

Mineral  Components  of  Milk. 

In  per  cent,  of  Milk.    In  per  cent,  of  Ash. 

Potassium  oxid  (K2O)  19  per  et.  25.64  per  ct. 

Sodium  oxid  (Na^O)  '  .09  12.45 

Lime  (CaO) 18  24.58 

Magnesia  (MgO) 02  3.09 

Iron  oxid  (FeaO.^)  002  .34 

Phosphoric  anhydrid  (P2O5).     .16  .                21.24 

Chlorin  (CI) 12  16.34 

.762perct.  103.68  per  ct. 

Less  oxygen,  corresponding  to 

Chlorin 012  3.68 

.75  100.00 

The  combinations  in  which  the  preceding  bases  and 
acids  are  contained  in  the  milk  are  not  known  with  cer- 
tainty. According  to  Soldner,  36  to  56  per  cent,  of  the 
phosphoric  acid  found  in  milk,  and  from  53  to  72  per 
cent,  of  the  lime,  are  present  in  suspension  in  the  milk 
as  di-  and  tri-calcium  phosphates,  and  may  be  filtered 
out  by  means  of  Chamberland  filters  (18),  or  by  long 
continued  centrifuging  (Babcock^).  The  rest  of  the  ash 
constituents  are  dissolved  in  the  milk  serum. 

The  ash  content  of  normal  cows'  milk  varies  but  little, 
as  a  rule  only  between  .  6  and  .  9  per  cent. ,  with  an  aver- 
age of  .  7  per  cent.  Milk  with  a  high  fat  content  gen- 
erally contains  about  .8  per  cent,  of  ash;  strippers'  milk 
always  has  a  high  ash  content,  at  times  even  exceeding 
one  per  cent.  Ordinarily,  the  mineral  constituents 
are,  however,  the  components  of  milk  least  liable  to 
variations. 

21.  Other  Components.  Besides  the  milk  constituents 
enumerated  and  described  in  the  preceding  pages,  nor- 

1  Wis.  experiment  station,  twelfth  report,  p.  93. 


Composition  of  Milk  and  Its  Products.  19 

mal  milk  contains  a  number  of  substances  which  are 
present  in  but  small  quantities  and  have  only  scientific 
interest,  such  as  the  milk  gases  (carbonic  acid,  oxygen, 
nitrogen),  citric  acid,  lecithin,  eholesterin,  urea,  hypo- 
xanthin,  lactochrome,  etc. 

22.  Average  Composition.  The  average  percentage 
composition  of  cows'  milk  will  be  seen  from  table  I  in 
the  Appendix.  The  following  statement  shows  the  limits 
within  which  the  components  of  normal  American  cows' 
milk  are  likely  to  come: 

Minimum.  Maximum.  Average. 

Water 82.0perct.  90.0perct.  87.4  per  ct. 

Fat 2.3  7.8  3.7 

Casein  and  albumen 2.5  4.6  3.2 

Milk  sugar 3.5  6.0  5.0 

Ash 6  .9  .7 

23.  Colostrum  Milk.  The  liquid  secreted  directly  after 
parturition  is  known  as  colostrum  milk  or  biestings.  It 
is  a  thick,  yellowish,  viscous  liquid;  its  high  content  of 
albumen  and  ash  is  characteristic,  and  also  its  low  con- 
tent of  milk  sugar.  Owing  to  the  large  quantity  of 
albumen  which  colostrum  contains,  it  will  coagulate  on 
being  heated  toward  the  boiling  point.  In  the  course  of 
four  to  five  days  the  secretion  of  the  udder  gradually 
changes  from  colostrum  to  normal  milk;  the  milk  is  con- 
sidered fit  for  direct  consumption  or  for  the  manufacture 
of  cheese  and  butter,  when  it  does  not  coagulate  on  boil- 
ing and  is  of  normal  appearance  as  regards  color,  taste, 
and  other  properties.  For  composition  of  colostrum 
milk,  see  Appendix /Y2ih\Q  I. 

24.  Composition  of  milk  products.  In  addition  to  its 
use  for  direct  consumption,  milk  is  the  raw  material  from 


20  Testing  Milk  and  Its  Products. 

which  cream,  butter,  cheese,  and  condensed  milk  are  ob- 
tained. 

When  milk  is  left  standing  for  some  time  or  subjected 
to  centrifugal  force,  it  will  separate  into  two  distinct 
parts,  cream  and  s/cm  milk.  The  proportion  of  each  part 
which  is  obtained  and  their  chemical  composition  will  de- 
pend on  the  method  by  which  the  separation  is  effected;  in 
the  so-called  gravity  process  where  the  cream  is  separated 
on  standing — either  in  shallow  pans  in  the  air,  or  in  deep 
cans,  submerged  in  cold  water — a  less  complete  separa- 
tion is  reached,  less  skim  milk  being  obtained  and  this 
being  richer  in  fat  than  when  the  separation  takes  place 
through  the  action  of  centrifugal  force. 

In  modern  creameries  the  milk  is  now  generally  skim- 
med by  means  of  cream  separators.  Separator  cream  will 
contain  from  15  to  50  per  cent,  of  fat,  according  to  the 
adjustment  of  the  separator  and  of  the  milk  supply;  ordi- 
narily it  contains  about  25  per  ct.  of  fat.  Cream  of  aver- 
age quality,  in  addition  to  the  fat  content  given,  consists 
of  about  66  per  ct.  of  water,  3.8  per  ct.  casein  and  albu- 
men, 4.3  per  ct.  milk  sugar,  and  .5  per  ct.  ash. 

The  skim  milk  is  made  up  of  the  milk  serum  (15)  and  a 
small  amount  of  fat,  viz.,  toward  .4perct.  when  obtained 
by  the  gravity  process,  and  less  than  .2  per  ct.  in  the 
case  of  separator  skim  milk.  Milk  set  in  shallow  pans 
in  the  air,  or  in  deep  cans  in  water  above  60°  F.,  will 
give  skim  milk  containing  one-half  to  over  one  per  ct.  of 
fat.  Skim  milk  is  used  as  a  food  for  young  farm  animals 
or  as  human  food,  and  in  this  country  only  in  excep- 
tional cases,  for  the  manufacture  of  cheese. 

25.  Cream  is  used  for  the  manufacture  of  butter  or  for 
direct  consumption.     In  the  former  case  a  certain  amount 


Composition  of  Milk  and  Its  Products.  21 

of  acidity  is  generally  allowed  to  develop  therein  pre- 
vious to  the  churning  process.  This  secures  a  more 
complete  churning  and  produces  peculiar  flavors  in  the 
butter,  without  which  it  would  seem  insipid  to  the  ma- 
jority of  people  in  this  country.  Nearly  all  American 
butter  is  salted  before  being  placed  on  the  market.  Salt 
is  a  preservative  and  for  a  limited  length  of  time  pre- 
vents butter  from  spoiling.  Unsalted  butter  made  from 
sweet  cream  is  a  common  food  article  in  Southern  and 
Middle  Europe,  but  only  an  insignificant  amount  is  man- 
ufactured and  consumed  in  America;  salted  butter  made 
in  Europe  also  contains  considerably  less  salt  than  Amer- 
ican butter  (see  Appendix,  Table  I).  Butter  contains  all 
the  fat  of  the  cream  but  a  small  portion  which  goes  into 
the  butter  milk,  and  a  small  unavoidable  mechanical  loss 
incident  to  the  handling  of  the  products.  Butter  should 
contain  at  least  80  per  ct.  of  fat  and  ordinarily  contains 
about  83  per  ct. ;  besides  this  amount  of  fat,  butter  is  gen- 
erally composed  of  water,  about  13  per  ct. ,  curd  and 
milk  sugar  1  per  ct.,  and  salt  3  per  ct. 

Butter  milk  is  similar  to  skim  milk  in  composition,  but 
varies  much  more  than  this  product,  according  to  the 
acidity,  temperature,  and  thickness  of  the  cream,  and 
other  churning  factors.  It  contains  about  9  per  ct.  of 
solids,  viz.,  milk  sugar  (and  lactic  acid)  4  perct.,  casein 
and  albumen  4  per  ct.,  fat  .3  per  ct.,  and  ash  .7  perct. 

26.  The  quantities  of  butter  and  by-products  obtained 
in  the  manufacture  of  butter  are  as  follows:  1000  lbs  of 
milk  of  average  quality  will  give  about  850  lbs.  of  skim 
milk  and  145  lbs.  of  cream  (separator  slime  and  mechan- 
ical loss,  5  lbs.);  this  amount  of  cream  will  make  about 
42  lbs.  of  butter  and  100  lbs.  of  butter  milk  (mechanical 
loss,  3  lbs.). 


22  Testing  Milk  and  Its  Products. 

27.  In  the  manufacture  of  American  cheddar  cheese, 
whole  milk  is  heated  to  about  86°  F., and  a  small  amount 
of  rennet  extract  is  added,  which  coagulates  the  caseiD; 
the  albumen  of  the  milk  is  not  precipitated  by  rennet 
and  remains  in  solution  (18).  ''Green"  cheese, as  taken 
from  the  press,  is  made  up,  roughly  speaking,  of  37  per 
ct.  of  water,  34  per  ct.  of  fat,  24  per  ct.  of  albuminoids 
(nearly  all  casein),  and  about  5  per  ct.  of  milk  sugar, 
lactic  acid, and  ash  (largely  salt).  In  the  curing  of  cheese 
there  is  some  drying  off,  but  the  main  changes  occur  in 
the  breaking  up  of  the  firm  curd  into  soluble  and  digest- 
ible nitrogenous  compounds,  peptons,  amids,  etc. 

Whey  is  the  by-product  obtained  in  the  manufacture 
of  cheese.  It  consists  of  water  and  less  than  7  per  ct.  of 
solids;  of  the  latter  about  5  per  ct.  is  milk  sugar,  .8  per 
ct.  albumen,  .6  per  ct.  ash,  and  .3  per  ct.  fat.  Whey  is 
generally  used  for  feeding  farm  animals;  it  is  the  raw- 
product  from  which  milk  sugar  and  whey  cheese  are  made. 

28.  Condensed  Milk  is  manufactured  from  whole  milk 
or  from  partially  skimmed  milk.  In  many  brands  a  large 
quantity  of  sugar  (25  per  ct.  or  more)  is  added  to  the 
condensed  milk  in  the  process  of  manufacture  so  as  to 
secure  perfect  keeping  quality  in  the  product.  Brands 
to  which  no  sugar  has  been  added  are  also  on  the  market, 
and  in  case  of  such  brands  the  relation  between  the  var- 
ious solid  constituents  of  the  condensed  milk  will  be  es- 
sentially the  same  as  that  between  the  constituents  of 
milk  solids.  Condensed  milk  should  contain  at  least  10 
per  ct.  of  fat,  and  must  be  free  from  preservatives  and 
all  other  foreign  substances  (except  sugar). 

Tables  are  given  in  the  Appendix  showing  the  average 
composition  of  the  various  milk  products. 


CHAPTEE  II. 
SAMPLING  niLK. 

29.  The  butter  fat  in  milk  is  not  in  solution, like  sugar 
dissolved  in  water,  but  the  minute  fat  globules  or  drops, 
in  which  form  it  occurs,  are  held  in  suspension  in  the 
milk  serum  (17).  Being  lighter  than  the  serum,  the  fat 
globules  have  a  tendency  to  rise  to  the  surface  of  the  milk. 
If,  therefore,  a  sample  of  milk  is  left  standing  for  even  a 
short  time,  the  upper  layer  will  contain  more  fat  than  the 
lower  portion.  This  fact  should  always  be  borne  in  mind 
when  milk  is  sampled.  The  rapidity  with  which  fat 
rises  in  milk  can  be  easily  demonstrated  by  allowing  a 
quantity  of  sweet  milk  to  stand  in  a  cylinder  or  a  milk 
can  for  a  few  minutes,  and  testing  separately  the  top, 
middle  and  bottom  layer  of  this  milk. 

The  amount  of  mixing  necessary  to  evenly  distribute 
the  constituents  of  milk  throughout  its  mass  may  be  as- 
certained by  adding  a  few  drops  of  cheese  color  to  a  quart 
of  milk.  The  yellow  streaks  through  the  milk  will  be 
noticed  until  it  has  been  poured  several  times  from  one 
vessel  to  another,  when  the  milk  will  have  a  uniform 
pale  yellow  color.  Stiring  with  a  stick  or  a  dipper  will 
not  produce  .m  even  mixture  so  quickly  or  so  complete- 
ly as  pouring  the  milk  a  few  times  from  one  vessel  to 
another;  in  sampling  milk  for  testing  it  should  always 
be  mixed  by  pouring,  just  before  the  milk  is  measured 
into  the  bottle;  if  several  tests  are  made  of  a  sample,  the 
milk  should  be  poured  before  each  sampling. 


24  Testing  Milk  and  Its  Products. 

30.  Partialfy  churned  milk.  A  secood  difficulty  some- 
times met  with  ia  sampling  whole  milk  arises  from  the 
fact  that  a  part  of  the  butter  fat  may  be  separated  in  the 
form  of  small  butter  granules,  by  too  zealous  mixing  or 
by  reckless  shaking  in  preparing  the  sample  for  testing. 
This  will  happen  most  readily  in  case  of  milk  from  fresh 
%ws  or  with  milk  containing  exceptionally  large  fat 
globules.  When  some  of  the  butter  granules  are  thus 
churned  out,  they  quickly  rise  to  the  surface  of  the  milk 
after  pouring  and  cannot  again  be  incorporated  in  the 
milk  by  simple  mixing;  it  is,  therefore,  impossible  to 
obtain  a  fair  sample  of  such  milk  for  testing  without  tak- 
ing special  measures  which  will  be  explained  in  the  fol- 
lowing. The  granules  of  butter  may  be  so  small  as  to 
pass  into  the  pipette  with  the  milk  and  the  quantity 
measured  thus  contain  a  fair  proportion  of  them,  but 
they  will  be  found  sticking  to  the  inside  of  the  pipette 
when  this  is  emptied,  and  thus  fail  to  be  carried  into  the 
test  bottle  with  the  milk. 

A  similar  partial  churning  of  the  milk  will  sometimes 
take  place  in  the  transportation  cans.  When  such  milk 
is  received  at  the  factory,  the  butter  granules  are  caught 
by  the  strainer  cloth  through  which  the  milk,  is  poured, 
and  are  thus  lost  both  to  the  factory  and  to  the  farmer. 
This  separated  fat  cannot  be  put  into  the  cream  or  added 
to  the  granular  butter,  without  running  the  risk  of  mak- 
ing mottled  butter,  and  it  will  not  enter  into  the  sample 
of  milk  taken  for  testing  purposes. 

When  milk  samples  are  sent  by  mail  or  express  in 
small  bottles,  or  carried  to  the  place  of  testing,  they 
often  arrive  with  lumps  of  butter  floating  in  the  milk  or 


V^^J^ 


Sampling  Milk,  25 

sticking  to  the  glass.  This  churning  of  the  milk  can  be 
easily  prevented  by  completely  filling  the  bottle  or  the  can. 
If  there  is  no  space  left  for  the  milk  in  which  to  splash 
around,  the  fat  will  not  be  churned  out  in  transit. 

31.  Approximately  accurate  results  may  generally  be 
obtained  with  a  partially  churned  sample  of  milk,  if  a 
teaspoonful  of  ether  be  added  to  it.  After  adding  the 
ether,  cork  the  bottle  and  shake  it  until  the  lumps  of 
butter  are  dissolved.  This  ether  solution  of  the  butter 
will  mix  with  the  milk,  and  from  the  mixture  a  fairly 
satisfactory  sample  may  generally  be  taken.  The  dilution 
of  milk  by  the  ether  introduces  an  error  in  the  testing, 
and  only  the  smallest  quantity  of  ether  necessary  to  dis- 
solve the  lumps  of  butter  should  be  used.  If  desired,  a 
definite  quantity  of  ether,  say  five  per  cent,  of  the  vol- 
ume of  the  sample  of  milk  to  be  tested,  may  be  added; 
in  such  cases  the  result  of  the  test  must  be  increased  by 
the  per  cent,  of  ether  added. 

Example.— To  a  4-oz.  sample  (120  cc.)  of  partially  churned 
milk,  5  per  cent,  or  6  cc,  of  common  ether  are  added;  tbe  mix- 
ture gives  an  average  test  of  4.2  per  cent.  The  test  must  be  in- 
creased by  ^1^x4. 2 =.21,  and  the  original  milk  therefore  con- 
tained 4.2+.21=4.41  per  cent,  of  fat. 

Milk  containing  ether  must  be  mixed  cautiously  with 
acid  so  as  to  avoid  loss  of  the  contents  of  the  bottle  by  the 
sudden  boiling  of  the  ether  due  to  the  heat  evolved. 

Instead  of  adding  ether  to  partially  churned  samples, 
the  milk  may  be  heated  to  about  110°  F.  for  a  few  min- 
utes, so  as  to  melt  the  butter  granules;  the  sample  is  now 
shaken  vigorously  until  a  uniform  mixture  of  milk  and 
melted  butter  is  obtained,  and  a  pipetteful  then  quickly 
drawn  from  the  sample. 


26  Testing  Milk  and  Its  Products. 

32.  Sampling  sour  milk.  When  milk  becomes  sour,  the 
casein  is  coagulated  aud  the  mechanical  condition  of  the 
milk  thereby  changed  so  as  to  render  difficult  a  correct 
sampling.  The  butter  fat  is  not,  however,  changed  in 
the  process  of  souring;  this  has  been  shown  by  one  of  us, 
among  others,  in  a  series  of  tests  which  were  measured 
from  one  sample  ot  sweet  milk  into  six  test  bottles. 
A  test  of  the  milk  in  one  of  these  test  bottles  was  made 
every  month  for  six  months,  and  approximately  the  same 
amount  of  fat  was  obtained  in  the  tests  throughout  the 
series,  as  was  found  originally  in  the  milk  when  tested 
in  a  sweet  condition.^  If  the  milk  is  in  condition  to  be 
sampled,  its  souring  does  not  therefore  interfere  with  its 
being  tested  by  the  Babcock  test  or  with  the  accuracy  of 
the  results  obtained. 

In  order  to  facilitate  the  sampling  of  sour  or  loppered 
milk,  some  chemical  may  be  added  which  will  re  dissolve 
the  coagulated  casein  and  produce  a  uniform  mixture  that 
can  be  readily  measured  with  a  pipette.  Any  alkali 
(powdered  potash  or  soda,  or  liquid  ammonia)  will  pro- 
duce this  effect.  Only  a  very  small  quantity  of  powdered 
alkali  is  necessary  for  this  purpose.  The  complete  action 
of  the  alkali  on  sour  milk  requires  a  little  time,  and  the 
operator  should  not  try  to  hasten  the  solution  by  adding 
too  much  alkali.  An  excess  of  alkali  will  often  cause 
such  a  violent  action  of  the  sulfuric  acid  on  the  milk  to 
which  the  acid  is  added  (on  account  of  the  heat  generated 
or  the  presence  of  carbonates  in  the  alkali)  that  the  mix- 
ture will  be  thrown  out  of  the  neck  of  the  test  bottle  when 


1  See  Hoard's  Dairyman,  April  8, 1892.    The  same  holds  true  for  cream, 
as  shown  by  Winton  ( U.  S.  Dept.  Agr.,  Div.  of  Chemistry,  bull.  43,  p.  112). 


Sampling  Milk.  27 

this  is  shaken  in  mixing  the  milk  and  the  acid  (37). 
When  powdered  alkali  is  added  to  the  milk,  it  should  be 
allowed  to  stand  for  a  while,  with  frequent  shaking,  until 
the  curd  is  all  dissolved  and  an  even  translucent  liquid 
is  obtained.  Such  milk  may  become  dark -colored  by 
the  action  of  the  alkali,  but  this  color  does  not  interfere 
with  the  accuracy  of  the  test. 

Instead  of  powdered  soda  or  potash, .  these  substances 
dissolved  in  water  (soda  or  potash  lye),  or  strong  am- 
monia water,  may  be  used  for  the  purpose  of  dissolving 
the  coagulated  casein  in  a  sample  of  sour  milk.  Iq  this 
case,  a  definite  proportion  of  alkali  solution  must,  how- 
ever, be  taken,  5  per  cent,  of  the  volume  of  milk  being 
usually  sufficient,  and  the  results  obtained  are  increased 
accordingly.     (See  example  cited  on  p.  25. ) 

33.  Sampling  frozen  milk.  When  milk  freezes,  it  sep- 
arates into  two  distinct  portions:  Milk  crystals,  largely 
made  up  of  water,  with  a  small  admixture  of  fat  and 
other  solids,  and  a  liquid  portion,  containing  nearly  all 
the  solids  of  the  milk.  In  sampling  frozen  milk  it  is 
therefore  essential  that  both  the  liquid  and  the  frozen 
part  be  warmed  and  mixed  thoroughly  by  pouring  gently 
back  and  forth  from  one  vessel  into  another;  the  sample 
is  then  taken  and  the  test  proceeded  with  in  the  ordinary 
manner  (36). 


CHAPTEE  III. 

THE  BABCOCK  TEST. 

34.  The  Babcock  test  is  founded  on  the  fact  that  strong 
sulfuric  acid  will  dissolve  all  non-fatty  solid  constituents 

of  milk  and  other 
dairy  products,  and 
wi)l  set  free  the  fat. 
This  will  separate  on 
standing,  but  to  effect 
a  speedy  and  complete 
separation,  the  bottles 
holding  the  mixture 
of  milk  and  acid  are 
placed  in  a  centrifugal 
machine,  a  so-called 
tester  J  and  whirled  for 
four  minutes;  hot 
water  is  then  added  so 
as  to  bring  the  liquid 
fat  into  the  graduated 
neck  of  the  test  bot- 
tles, and  after  a  re- 
peated whirling,  the 
length  of  the  column 

Fig.  4.    The  first  Babcock  tester  made.  ^^  ^  .  t      «.    i 

of  fat  IS  read  off,  show- 
ing the  per  cent,   of  fat  contained  in  the  sample  tested. 


/  The  Bahcock  Test.  29 

•^  Sulfuric  acid  is  preferable  to  other  strong  mineral 
acids  for  the  purpose  mentioned,  on  account  of  its  affinity 
to  water;  when  mixed  with  milk,  the  mixture  heats 
greatly,  thus  keeping  the  fat  liquid  without  the  applica- 
tion of  artificial  heat  and  rendering  possible  a  distinct 
reading  of  the  column  of  fat  brought  into  the  neck  of  the 
test  bottles. 

So  far  as  is  known,  any  kind  of  milk  can  be  tested  by 
the  Babcock  test.  Breed,  period  of  lactation,  quality  or 
age  of  the  milk  is  of  no  importance  in  using  this  method, 
so  long  as  a  fair  sample  of  the  milk  can  be  secured.  In 
case  of  samples  of  milk  or  other  dairy  products  rich  in 
solids  it  requires  a  little  more  effort  to  obtain  a  thorough 
mixture  with  the  acid  than  with  dairy  products  low  in 
solids,  like  skim  milk  or  whey,  which  may  be  readily 
mixed  with  the  acid. 

A. — Directions  for  Making  the  Test. 

35.  The  various  steps  in  the  manipulation  of  the  Bab- 
cock test  are  discussed  in  the  following  pages;  attention 
is  drawn  to  the  difficulties  which  the  beginner  and  others 
may  encounter  in  the  use  of  the  test,  and  the  necessary 
precautions  to  be  observed  in  order  to  obtain  accurate 
and  satisfactory  results  are  explained  in  detail.  The 
effort  has  been  to  treat  the  subject  exhaustively  and  from 
a  practical  point  of  view,  so  that  persons  as  yet  unfamil- 
iar with  the  test  may  turn  to  the  pages  of  this  book  for 
help  in  any  difficulties  which  they  may  meet  in  their 
work  in  this  line. 

36.  Sampling.  The  sample  to  be  tested  is  first  mixed 
by  pouring  the  milk  from  one  vessel  to  another  two  or 


30 


Testing  Milk  and  Its  Products. 


three  times  so  that  every  portion  thereof  will 
contain  a  uniform  amount  of  butter  fat  (29). 
The  measuring  pipette  which  has  a  capacity  of 
17.6  cubic  centimeters  (see  fig.  6),  is  filled  with 
the  milk  immediately  after  the  mixing  is  com- 
pleted, by  sucking  the  milk  into  it  until  this 
rises  a  little  above  the  mark  around  the  stem  of 
the  pipette;  the  forefinger  is 
then  quickly  placed  over  the  end 
of  the  pipette  before  the  milk 
runs  down  below  the  mark.  By 
slightly  releasing  the  pressure  of 
the  finger  on  the  end  of  the 
pipette,  the  milk  is  now  allowed 
to  run  down  until  it  just  reaches 
the  mark  on  the  stem;  the  quan- 
tity of  milk  contained  in  the 
pipette  will  then,  if  this  is  cor- 
rectly made,  be  exactly  17.6  cc. 
The  finger  should  be  dry  in 
measuring  out  the  milk  so  that 
the  delivery  of  milk  may  be  read- 
ily checked  by  gentle  pressure  on 
i  tSk  the  upper  end  of  the  pipette. 
Wm  The  point  of  the  pipette  is 
now  placed  in  the  neck  of  a  Bab- 
cock  test  bottle  (fig.  5),  and  the 
milk  is  allowed  to  flow  slowly 
down  the  inside  of  the  neck.  Care 
must  be  taken  that  none  of  the 
milk  measured  out  is  lost  in  this 
transfer.  The  portion  of  the  milk 
remaining  in  the  point  of  the  pip- 
^'''- teStotue."""''  et,te  is  blown  into  the  test  bottle. 


nml 


The  Babcock  Test. 


31 


The  best  and  safest  manDer  of  holding  the  bottle  and 
the  pipette  in  this  transfer  is  shown  in  fig.  7.  Fig.  8 
shows  a  position  which  should  be  avoided,  since  by  hold- 
ing the  bottle  in  this  way,  there  is  danger  that  some  of 
the  milk  may  com- 
pletely fill  the  neck 
of  the  bottle,  and  as  a 
result,  flow  over  the 
top  of  the  neck. 

Pipettes,  the  lower 
part  of  which  slip 
readily  into  the  necks 
of  the  test  bottles, 
may  be   emptied   by 

lowering  the   pipette     Ar^  into  the  neck  of  the  bot- 

tle till  it  rests  on  its  rim, 
when  the  milk  is  allowed 
to  run  into  the  test 
bottle. 

37.  Adding  Acid.  The 
acid  cylinder  (fig.  9) 
holding  17.  Sec,  is  filled 
to  the  mark  with  sulfuric 
acid  of  a  specific  gravity 
of  1.82-1.83.  This 
amount  of  acid  is  care- 
fully poured  into  the 
test  bottle  containing  the 
milk.  In  adding  the 
acid,  the  test  bottle  is  conveniently  held  at  an  angle 
(see  fig.  7),  so  that  the  acid  will  follow  the  wall  of  the 
bottle  and  not  run  in  a  small  stream  into  the  center  of 
the  milk,  the  bottle  being  slowly  turned  around  and  the 


Fig. 


.    The  right  way  of  emptying 
pipette  into  test  bottle. 


32 


Testing  Milk  and  Its  Products. 


neck  thus  cleared  of  adhering  milk.  By  pouring  the 
acid  into  the  middle  of  the  test  bottle,  there  is  also 
a  danger  of  completely  filling  this  with  acid,  in  which 
case  the  plug  of  acid  formed  will  be  pushed  over  the 
edge  of  the  neck  by  the  ex- 
pansion of  the  air  in  the  bot- 
tle, and  may  be  spilled  on  the 
hands  of  the  operator. 

The  milk  and  the  acid  in 
the  test  bottle  should  be  in 
two  distinct  layers,  without 
a  black  portion  of  partially 
mixed  liquids  between  them. 
Such  a  dark  layer  is  often  fol- 
lowed by  an  indistinct  separa- 
tion of  the  fat  in  the  final 
reading.  The  cause  of  this 
may  be  that  a  partial  mixture 
of  acid  and  milk  before  the 
acid  is  diluted  with  the  water 
of  the  milk  may  bring  about 
too  strong  an  action  of  the 
acid  on  the  milk,  and  the  fat 
in  this  small  por- 
tion maybe  slightly 
charred  by  the 
strong  acid.  The 
appearance  of 
black  flocculent  matter  in  or  below  the  column  of  fat 
which  generally  results,  in  either  case  renders  a  correct 
measurement  of  fat  difficult  and  at  times  even   impos- 


FiG.  8. 


The  wrong  way  of  emptying  pipette 
into  test  botile. 


The  Bahcock  Test. 


33 


sible;  if  the  black  specks  occur  in  the  fat  column  itself, 
the  readings  are  apt  to  be  too  high;  if  below  it,  the  diffi- 
culty comes  in  deciding  where  the  column  of  fat  begins. 
38.  Mixing  milk  and  acid.  After  adding  the  acid,  this  is 
carefully  mixed  with  the  milk  by  giving  the  test  bottle  a 
rotary  motion.  In  doing  this,  care  should  be  taken  that 
none  of  the  liquid  is  shaken  into  the  neck  of  the  test  bottle. 
When  once  begun,  the  mixing  should  be  continued  until 
completed;  a  partial  and  interrupted  mixing  of  the  liquids 
will  often  cause  more  or  less  black  material 
to  separate  with  the  fat  when  the  test  is 
finished.  Clots  of  curd  which  separate  at 
first  by  the  action  of  the  acid  on  the  milk, 
must  be  entirely  dissolved  by  continued  and 
careful  shaking  of  the  bottle.  Beginners 
sometimes  fail  to  mix  thoroughly  the  milk 
and  the  acid  in  the  test  bottle.  As  the  acid 
is  much  heavier  than  the  milk,  a  thin  layer 
of  it  is  apt  to  be  left  unnoticed  at  the  bot- 
tom of  the  bottle,  unless  this  is  vigorously 
shaken  toward  the  end  of  the  operation. 
The  mixture  becomes  hot  by  the  action  of  the  acid  on 
the  water  in  the  milk  and  turns  dark  colored,  owing  to 
the  effect  of  the  strong  sulfuric  acid  on  the  nitrogenous 
constituents  and  the  sugar  of  milk. 

Colostrum  milk  or  milk  from  fresh  cows  will  form  a 
violet  colored  mixture  with  the  acid,  due  to  the  action 
of  the  latter  on  the  albumen  present  in  such  milk  in  con- 
siderable quantities  (23). 

When  milk  samples  are  preserved  by  means  of  potas- 
ium  bichromate  (188),  and  so  much  of  this  material  has 


Fig.  9.    17  5  cc 
acid  cylinder. 


34  Testing  Milk  and  Its  Ftoduds. 

been  added  that  the  milk  has  a  dark  yellow  or  reddish 
color,  the  mixture  of  milk  and  acid  will  turn  greenish 
black,  and  a  complete  solution  is  rendered  extremely 
difficult  on  account  of  the  toughening  eifect  of  the  bichro- 
mate on  the  precipitated  cas'^in.  This  difficulty  is  still 
more  pronounced  with  milk  preserved  with  formalde- 
hyd. 

39.  Whirling  bottles.  After  the  milk  and  the  acid 
have  been  completely  mixed,  the  test  bottle  is  at  once 
place!  in  the  centrifugal  machine  or  tester  and  whirled 
for  four  or  five  minutes  at  a  speed  of  600  to  1200  revo- 
lutions per  minute,  the  proper  speed  being  determined 
by  the  diameter  of  the  tester  (66).  It  is  not  absolutely 
necessary  to  whirl  the  test  bottles  in  the  centrifuge  as 
soon  as  the  milk  and  the  acid  are  mixed,  although 
this  method  of  procedure  is  much  to  be  preferred; 
they  may  be  left  in  this  condition  for  any  reasonable 
length  of  time  (24  hours,  if  necessary)  without  the 
test  being  spoiled.  If  left  until  the  mixture  becomes 
cold,  the  bottles  should,  however,  be  placed  in  warm 
water  (of  about  160°  F. )  for  about  15  minutes  before 
whirling. 

Four    minutes    at    full   speed    is    sufficient   for   the 
first   whirling    of   the    test   bottles   in    the    centrifuge; 
'  this  will   bring  all  fat   to  the  surface  of  the  liquid  in 
the  bottle. 

40.  Adding  water.  Hot  water  is  now  added  by  means  of 
a  pipette  or  some  special  device  (10  in  fig.  58),  until  the 
bottles  are  filled  to  near  the  scale  on  the  neck  (80).  The 
bottles  are  whirled  again  at  full  speed  for  one  minute, 
and  hot  water  added  a  second  time,  until  the  lower  part 


The  Babcock  Test.  35 

of  the  column  of  fat  comes  within  the  scale  on  the  neck 
of  the  test  bottle,  preferably  to  the  1  or  2  per  cent, 
mark,  so  as  to  allow  for  the  sinking  of  the  column  of  fat, 
due  to  the  gradual  cooling  of  the  contents  of  the  bottle! 
By  dropping  the  water  directly  on  the  fat  in  the  second 
filling,  the  column  of  fat  will  be  washed  free  from  light 
flocculent  matter,  which  might  otherwise  be  entangled 
therein  and  render  the  reading  uncertain  or  even  too 
high.  A  final  whirling  for  one 
minute  completes  the  separation  of 
the  fat. 

4r.  Measuring  the  fat.  The  amount 
of  fat  in  the  neck  of  the  bottle  is 
measured  by  the  scale  or  gradua- 
tions on  the  neck.  Each  division 
of  the  scale  represents  two- tenths  of 
one  per  cent,  of  fat,  and  the  space 
filled  by  the  fat  shows  the  per  cent. 
of  butter  fat  contained  in  the  sam- 
ple tested. 

The  fat  is  measured  from  the 
lower  line  of  separation  between 
the  fat  and  the  water,  to  the  top  of 
the  fat  column,  at  the  point  h, 
shown  in  the  figure  10,  the  reading  -being  thus  taken 
from  a  to  6,  and  not  to  c  or  to  d.  Comparative  gravi- 
metric analyses  have  shown  that  the  readings  obtained 
in  this  manner  give  correct  results.  While  the  lower 
line  of  the  fat  column  is  nearly  straight,  the  upper  one 
is  curved,  and  errors  in  the  reading  are  therefore  easily 
made,  unless  the  preceding  rule  is  observed. 


SL 


=i_? 


Fig.  10.  Measuring  the 
column  of  fat.  in  a  Bab- 
cock test  bottle. 


36  Testing  Milk  and  Its  Products. 

The  fat  obtained  should  form  a  clear  yellowish  liquid 
distinctly  separated  from  the  acid  solution  beneath  it. 
There  should  be  no  black  or  white  sediment  in  or  below 
the  column  of  fat,  and  no  bubbles  or  foam  on  its  surface. 
The  bottles  must  be  kept  warm  until  the  readings  are 
made,  so  that  the  column  of  fat  will  have  a  sharply  de- 
fined upper  and  lower  meniscus. 

The  readings  should  be  made  when  the  fat  has  a  tem- 
perature of  about  140°  F.,  although  the  results  obtained 
will  not  be  appreciably  affected  if  the  temperature  falls 
below  120°.  The  fat  separated  in  the  Babcock  test  solid- 
ifies at  about  100°  F.  No  reading  should  be  attempted 
if  the  fat  is  partly  solidified,  as  it  is  impossible  to  get  an 
accurate  reading  in  this  case.^ 

42.  Headings  of  tests  of  milk  made  in  steam  turbine 
testers  with  tightly  closed  covers  which  prevent  the  free 
escape  of  exhaust  steam  (71)  will  come  .2  to  .3  per  cent,  too 
high  if  the  temperature  of  the  fat  is  allowed  to  rise  to 
that  of  the  exhaust  steam  during  the  process  of  whirling. 
In  such  cases  the  test  bottles  must  be  allowed  to  cool  to 
about  140°  (by  placing  them  in  water  of  this  tempera- 
ture for  a  few  minutes)  before  readings  are  taken. "^ 


1  The  effect  of  differences  in  the  temperature  of  the  fat  on  the  readings 
obtained  will  be  seen  from  the  following:  If  110  and  150°  F.  be  taken  as  the 
extreme  temperatures,  at  which  readings  are  made,  this  difference  of  40° 
F.  (22.3°  C.)  would  make  a  difference  in  the  volume  of  the  fat  column  ob- 
tained in  case  of  10  per  cent,  milk,  of  .000<>4  x2  x  22.3=.028544  cc,  or  .14  per 
cent.,  .00064  being  the  expansion  coefficient  of  pure  butter  fat  per  degree 
Centigrade  between  50  and  100°  C.{Zune,  Analyse  des  Beurres,  I,  871,  and  2,  the 
volume  of  the  fat  in  cc.  contained  in  17.6  cc.  of  10  per  cent.  milk.  On  5  per 
cent,  milk  this  extreme  difference  would  therefore  be  about  .07  percent, 
or  considerably  less  than  one-tenth  of  one  per  cent. 

2  See  Wis.  experiment  station  rep.  XVII,  p.  76. 


The  Babcock  Test. 


37 


Fig.  11. 


A  pair  of  dividers  will  be  found  convenient  for  meas- 
uring the  fat,  and  the  liability  of  error  in  reading 
is  decreased  by  their  use.  The  points 
of  the  dividers  are  placed  at  the  upper 
and  lower  limits  of  the  fat  column 
(from  a  to  b  in  fig.  10).  The  dividers 
are  now  lowered,  one  point  being 
placed  at  the  zero  mark  of  the  scale, 
and  the  mark  at  which  the  other  point 
touches  the  scale  will  show  the  per 
cent,  of  fat  in  the  sample  tested.  The 
dividers  must  be  tight  in  the  joint  to 
be  of  use  for  this  purpose. 

42a.  A  simple  device  for  measuring 
the  fat  column  in  the  Babcock  test  has 
been  made  by  Mr.  Fred  Lutley  of  Winnipeg  Dairy  School  ^ 
(fig.  11).  The  instrument  consists  of  two  parts:  a  wooden 
piece,  a,  sliding  inside  of  6,  which  is  made  of  tin  and  is  open 
on  one  side,  leaving  the  corrugated  part  of  a  accessible,  so 
that  this  may  be  raised  or  lowered  with  the  thumb.  A 
steel  pointer  is  attached  to  each  part.  The  column  of  fat 
in  a  test  bottle  is  read  off  with  this  instrument  in  the  same 
way  as  with  a  pair  of  dividers. 

B.  —Discussion  of  the  Details  of  the 
Babcock  Test. 
43.  The  main  points  to  be  observed  as  to  apparatus 
and  testing  materials  in  order  to  obtain  correct  and 
satisfactory  results  by  this  test  will  now  be  considered, 
and  such  suggestions  and  help  offered,  as  has  been  found 
desirable  from  an  extensive  experience  with  a  great 
variety  of  samplesof  milk,  apparatus,  and  accessories. 

1  N.  Y.  Produce  Review,  April  4, 1903. 


38  Testing  Milk  and  Its  Products. 

1. —  Glassware. 

44.  Test  bottles.  The  test  bottles  should  have  a 
capacity  of  about  50  cc,  or  less  than  two  ounces;  they 
should  be  made  of  well-annealed  glass  that  will  stand 
sudden  changes  of  temperature  without  breaking,  and 
should  be  sufficiently  heavy  to  withstand  the  maximum 
centrifugal  force  to  which  they  are  likely  to  be  subjected 
in  making  tests.  This  force  may,  on  the  average,  not  be 
far  from  30.65  lbs.  (see  ^Q)^  which  is  the  pressure  exerted 
in  whirling  the  bottles  filled  with  milk  and  acid  in  a 
centrifugal  machine  of  18  inches  diameter  at  a  speed  of 
800  revolutions  per  minute. 

Special  forms  of  test  bottles  used  in  testing  cream  and 
skim  milk  are  described  under  the  heads  of  cream,  and 
skim  milk  testing  (89,  90,  91,  99). 

When  17.6  cc,  or  18  grams  of  milk  (48)  are  measured 
into  the  Babcock  test  bottle,  the  scale  on  the  neck  of  the 
bottles  shows  directly  the  per  cent,  of  fat  found  in  the 
milk.  The  scale  is  graduated  from  0  to  10  per  cent. 
10  per  cent,  of  18  grams  is  1.8  grams.  As  the  specific 
gravity  of  pure  butter  fat  (i.  e.  its  weight  compared 
with  that  of  an  equal  quantity  of  pure  water)  at  the 
temperature  at  which  the  readings  are  made  (about  140° 
F. ),  is  0.9,  then  1.8  grams  of  fat  will  occupy  a  volume 
of  ^  =  2  cubic  centimeters.  The  space  between  the  0  and 
10  per  cent,  marks  on  the  necks  of  the  test  bottles  must 
therefore  hold  2  cc,  if  correctly  made.  The  scale  is 
divided  into  10  equal  parts,  each  part  representing  one 
per  cent.,  and  each  of  these  is  again  sub-divided  into 
five  equal  parts.     Each  one  of  the  latter  divisions  there- 


The  Babcocl'  Test  39 

fore  represents  two- tenths  of  one  per  cent,  of  fat  when 
17.6  cc.  of  milk  is  measured  out.  The  small  divisions 
are  sufficiently  far  apart  in  most  Babcock  test  bottles  to 
make  possible  the  estimation  of  one-tenth  of  one  per 
cent,  of  fat  in  the  samples  tested. 

As  the  necks  of  Babcock  test  bottles  vary  in  diameter, 
each  separate  bottle  must  be  calibrated  by  the  manufac- 
turers; the  lengtli  of  the  scale  is  not,  for  the  reason  given, 
apt  to  be  the  same  in  different  bottles.^ 

If  the  figures  and  lines  of  the  measuring  scale  become 
indistinct  by  use,  the  black  color  may  be  i-estored  by 
rubbing  a  soft  lead  pencil  over  the  scale,  or  by  the  use  of 
apiece  of  burnt  cork  after  the  scale  has  been  rubbed 
with  a  little  tallow.  On  wiping  the  neck  with  a  cloth  or 
a  piece  of  paper  the  black  color  will  show  in  the  etchings 
of  the  glass,  making  these  plainly  visible. 

45.  Marking  test  bottles.  Test  bottles  can  now  be 
bought  with  a  small  band  or  portion  of  their  neck  or 
body  ground,  or  "frosted,"  for  numbering  the  bottles 
with  a  lead  pencil.  Bottles  without  this  ground  label 
can  be  roughened  at  any  convenient  spot  by  using  a  wet 
fine  file  to  roughen  the  smooth  surface  of  the  glass.  There 
is  this  objection  to  the  latter  method  that  unless  carefully 
done,  it  is  apt  to  weaken  the  bottles  so  that  they  will 
easily  break,  and  to  both  methods,  that  the  lead  pencil 
marks  made  on  such  ground  labels  may  be  effaced  dur- 
ing the  test  if  the    bottles    are  not  carefully  handled. 


1  A  flat-bore  test  bottle  and  one  with  a  brass  collar  and  screw  used  for 
opening  and  closing  a  email  hole  in  the  neck  of  the  test  bottle  have  been 
placed  on  the  market  by  the  Wagner  Glass  Works  of  New  York.  Thrse 
have  been  tried  by  us,  but  no  particular  advantage  over  the  round- neck 
bottles  was  discovered. 


40 


Testing  Mdk  and  Its  Products. 


Small  strips  of  tin  or  copper  with  a  number  stamped 
thereon  are  sometimes  attached  as  a  collar  around  the 
necks  of  the  bottles.  They  are,  however,  easily  lost, 
especially  when  the  top  of  the  bottle  is  slightly  broken, 
or  at  any  rate,  are  soon  corroded  so  that  the  numbers 
can  only  be  seen  with  difficulty. 

The  best  and  most  permanent  label  for  test  bottles  is 
made  by  scratching  a  number  with  a  marking  diamond 
on  the  glass  di- 
rectly above  the 
scale  on  the  neck 
of  the  bottles  or 
by  grinding  a 
number  on  the 
bottle  itself.  In 
ordering  an  out- 
fit, or  test  bot- 
tles alone,  the  - 
operator    may 

specify  that  the  fig.  12.    Waste-acId  jar. 

bottles  are  to  be  marked  1  to  24,  or  as  many  as  are 
bought,  and  the  dealer  will  then  put  the  numbers  on 
with  a  marking  diamond. 

A  careful  record  should  be  kept  of  the  number  of  the 
bottle  into  which  each  particular  sample  of  milk  is  meas- 
ured. Mistakes  are  often  made  when  the  operator  trusts 
to  his  memory  for  locating  the  dififerent  bottles  tested  at 
the  same  time. 

46.  Cleaning  test  bottles.  The  fat  in  the  neck  of  the 
test  bottles  must  be  liquid  when  these  are  cleaned.  In 
emptying  the  acid  the  bottle  should  be  shaken  in  order 


The  Babcocl-  Test. 


41 


to  remove  the  white  residue  of  sulfate  of  lime,  etc.,  from 
the  bottom;  if  the  acid  is  allowed  to  drain  out  of  the 
bottle  without  shaking  it,  this  residue  will  be  found  to 


B 


Fig.  13.  Apparatus  for  cleaning  test  bottles.  A,  apparatus  in  position; 
the  water  flows  from  the  reservoir  through  the  iron  pipe  b  into  the  in- 
verted test  bottle  d  through  the  brass  tube  c,  screwed  Into  the  iron  pipe. 
B  shows  construction  of  the  rubber  support  on  which  the  tops  of  the  test 
bottles  rest;  /,  draining  sink. 

stick  very  tenaciously  to  the  bottom  of  the  bottle  in  the 
subsequent  cleaning  with  water. 

A  convenient  method  of  emptying  test  bottles  is  shown 
in  the  illustration  (fig.  12).     After  reading  the  fat  col- 


42 


Testing  Milk  and  Its  Products. 


%l 


® 


\ 


unin,  the  bottles  are  placed  neck  down,  in  the  half-inch 
holes  of  the  board  cover  of  a  five-gallon  stoneware  jar. 
An  occasional  shaking  while  the  liquid  is  running  from 
the  bottles  will  rinse  off  the  precipitate  of  sulfate  of 
lime.  A  thorough  rinsing  with  boiling  hot  water  by 
means  of  an  apparatus,  devised  by  one  of  us^  (see  fig.  13), 
is  generally  sufficient  to  remove  all  grease  and  dirt,  as 
well  as  acid  solution  from  the  inside  of  the  bottles. 
When  the  bottles  have  been  rinsed,  they  are  placed  in 
an  inverted  position  to  drain,  on  a  galvanized  iron  rack, 
as  shown  in  fig.  14,  where  they  are  kept  until  needed. 
The  outside  of  the 
bottles  should  occa- 
sionally be  wiped 
clean  and  dry. 

47.  The  amount  of 
unseen  fat  that  clings 
to  test  bottles  used 
for  testing  milk  or  cream,  is  generally  not  sufficient  to 
be  noticed  in  testing  whole  milk,  but  it  plays  an  im- 
portant part  in  testing  samples  of  separator  skim  milk. 
It  may  be  readily  brought  to  light  by  making  a  blank 
test  with  clean  water  in  bottles  used  for  testing  ordinary 
milk,  which  have  been  cleaned  by  simply  draining  the 
contents  and  rinsing  once  or  twice  with  hot  water;  at  the 
conclusion  of  the  test  the  operator  will  generally  find  that 
a  few  drops  of  fat  —  sometimes  enough  to  condemn  a 
separator  —  will  collect  in  the  neck  of  the  bottles. 

Boiling  hot  water  will  generally  clean  the  grease  from 
glassware  for  a  time,  but  all  test  bottles  should,  in  addi- 


\L 


Fig.  14.    Draining-rack  for  test  bottles. 


1  Farrington. 


The  Bdbcock  Test. 


43 


Fig.  15.    Tank  for  cleaning  test  bottles. 


tion,  be  given  an 
occasional  bath  in 
some  weak  alkali 
or  other  grease- 
dissolving  solution. 
Persons  doing  con- 
siderable milk  test- 
ing will  find  it  of 
advantage  to  pro- 
vide themselves 
with  a  small  cop- 
per tank,  which 
can  be  filled  with  a 
weak  alkali-solu- 
tion (figs.  15  and 
16).  After  having 
been  rinsed  with 
hot  water,  the  test 


bottles  are  placed  in  the  hot  solution  in  the  tank,  where 
they  may  be  left  completely  covered  with  the  liquid.     If 


Fig  16.    Rack  for  holding  test  bottles  in  tank  shown  in  fig.  15. 


44  Testing  Milk  and  Ks  Products. 

the  tank  is  provided  with  a  small  faucet  at  the  bottom, 
the  liquid  can  be  drawn  off  when  the  test  bottles  are 
wanted.  A  tablespoonful  of  some  cleaning  powder  to 
about  two  gallons  of  water  will  make  a  very  satisfactory- 
cleaning  solution;  sal  soda,  Gold  Dust,  Lewis'  lye  or  Bab- 
bitfs  potash  are  very  efficient  for  this  purpose.  The 
cleansing  properties  of  solutions  of  any  of  these  substances 
are  increased  by  warming  the  liquid.  The  test  bottles 
must  be  rinsed  twice  with  hot  water  after  they  are  taken 
from  this  bath. 

The  black  stains  that  sometimes  stick  to  the  inside  of 
test  bottles  after  prolonged  use,  can  be  removed  with  a 
little  muriatic  acid. 

An  excellent  cleaning  solution  may  be  made  of  one- 
half  pound  bichromate  of  potash  to  one  gallon  of  sul- 
furic acid  (Michels,  Am.  Cheesemaker,  Jan.  1903). 

48.  Pipette.  The  difference  in  the  weights  of  various 
samples  of  normal  milk  generally  falls  within  compara- 
tively narrow  limits;  if  a  given  volume  of  water  weighs 
one  pound,  the  same  volume  of  the  usual  grades  of  nor- 
mal milk  will  weigh  from  1.029  to  1.033  pounds,  or  on 
the  average,  1.03  lbs.  18  grams  of  water  measures  18 
cc.^;  18  grams  of  milk  will  therefore  take  up  a  smaller 
volume  than  18  cc,  viz:  18  divided  by  1.03,  which  is 
very  nearly  17.5.  This  is  the  quantity  of  milk  taken 
in  the  Babcock  test.  A  certain  amount  of  milk  will  ad- 
here to  the  walls  of  the  pipette  when  it  is  emptied,  and 

1  Cubic  centimeters  (abbreviated:  cc.)  are  the  standard  used  for  meas> 
uring  volume  in  the  metric  system,  similar  to  the  quart  or  pint  measure 
in  our  ordinary  system  of  measures.  One  quart  is  equal  to  a  little  less  than 
1,000  cubic  centimeters.  In  the  same  way,  grams  represent  weight,  like 
pounds  and  ounces.  One  cc.  of  water  at  4°<:entigrade  weighs  1  gram;  1,000 
grams  (=1  kilogram)  are  equal  to  2.2  lbs.  Avoirdupois.  (See  Appendix  for 
Comparisons  of  metric  and  customary  weights  and  measures.) 


The  Bdbcock  Test. 


45 


Fig.  17.     Pip- 
ette points— 
A,  proper con- 
struction; B, 
undesirable 
construction 


this  thin  film  has  been  found  to  weigh  about  one  tenth 
of  a  gram 5  consequently  17.6  cc.  has  been  adopted  as  the 
capacity  of  the  pipette  used  for  delivering 
18  grams  of  milk. 

For  convenience  in  measuring  the  milk, 
the  shape  of  the  pipette  is  of  importance. 
The  mark  on  the  stem  should  be  two  inches 
or  more  from  the  upper  end  of  the  pipette. 
The  lower  part  should  be  small  enough  to  fit 
loosely  into  the  neck  of  the  test  bottle,  and  not 
contracted  to  a  fine  hole  at  the  point;  the 
point  should  be  large  enough  to  allow  a 
quickemptyingof  the  pipette  (fig.  17). 

49.  Fool  Pipettes.  Soon  after  the  Babcock  test  began  to  be 
generally  used  at  creameries  as  a  method  of  paying  for  the  milk, 
a  creamery  supply  house  put  on  the  market  a  20  cc.  milk-meas- 
uring pipette,  which  was  claimed  to  show  the  exact  butter 
value  of  milk,  instead  of  its  content  of  butter  fat  as  is  the  case 
iu  using  the  ordinary  17.6  cc.  pipette.  A  20  cc.  pipette  will 
deliver  2.4  cc.  more  milk  than  a  17.6  cc.  pipette,  (or  13.6  per 
cent,  more),  and  the  results  obtained  by  using  these  pipettes 
will,  therefore,  be  about  13.6  per  cent,  too  high.  In  consider- 
ing the  subject  of  Overrun  (214)  it  is  noted  that  the  excess  of 
butter  yield  over  the  amount  of  fat  contained  in  a  certain  quan- 
tity of  milk  will  range  from  about  10  to  16  per  cent.,  or  on  the 
average,  about  12  per  cent.  20  cc.  pipettes  maj^,  therefore,  give 
approximately  the  yield  of  butter  obtained  from  a  quantity  of 
milk,  but  as  will  be  seen,  this  yield  is  variable,  according  to  the 
skill  of  the  butter  makerand  according  to  conditions  beyond  his 
control;  it  cannot  therefore  be  used  as  a  standard  in  the  same 
manner  as  the  fat  content  of  the  milk.  Similar  22  cc.  pipettes 
were  also  sent  out.  These  pipettes  created  a  great  deal  of  con- 
fusion during  the  short  time  they  were  on  the  market,  and 
were  popularly  termed  "fool  pipettes."  It  is  not  known  that 
any  of  these  pipettes  have  been  sold  of  late  years. 


46  Testing  Milk  and  Its  Products. 

A  recent  Wisconsin  law  makes  it  a  misdemeanor  to  use  other 
pipettes  than  17.6  cc.  ones  for  measuring  milk  where  this  is  paid 
for  by  the  Babcock  test.^ 

50.  Acid  measures.  A  17.5  cc.  glass  cylinder  (fig.  9) 
for  measuring  the  acid  is  generally  included  in  the  outfit, 
when  a  Babcock  tester  is  bought.  This  cylinder  answers 
every  purpose  if  only  occasional  tests  are  madej  the  acid 
is  poured  into  the  cylinder  from  the  acid  bottle  as 
needed,  or  a  quantity  of  acid  sufiQcient  for  the  number  of 
test  bottles  to  be  whirled  at  a  time,  is  poured  into  a  small 
glass  beaker  provided  with  a  lip,  or  into  a  small  porce- 
lain pitcher;  these  may  be  more  easily  handled  than  the 
heavy  acid  bottle,  and  the  acid  measure  is  then  filled 
from  such  a  vessel. 

Where  a  considerable  number  of  tests  are  made  regu- 
larly, the  acid  can  be  measured  into  the  test  bottles 
faster  and  with  less  danger  of  spilling,  by  using  some  one 
of  the  many  devices  proposed  for  this  purpose.  There 
is  some  objection  to  nearly  all  of  these  appliances,  auto- 
matic pipettes,  burettes,  etc.,  although  they  will  often 
give  good  satisfaction  for  a  time  while  new.  Sulfuric 
acid  is  very  corrosive,  and  operators  as  a  rule  take  but 
poor  care  of  such  apparatus,  so  that  it  is  a  very  difficult 
matter  to  design  a  form  which  will  remain  in  a  good  work- 
ing order  for  any  length  of  time.  Automatic  pipettes 
attached  to  acid  bottles  or  reservoirs,  to  prove  satisfac- 
tory, must  be  made  entirely  of  glass,  and  strong,  of  sim- 
ple construction,  tightly  closed  and  quickly  operated. 

51.  The  Swedish  acid-bottle  answers  these  requirements 
better  than  any  other  device  known  to  the  writers  at  the 
present  time.  Its  use  is  easily  understood  (see  fig.  18); 
it  gives  good  satisfaction  if  the  hole  in  the  glass  stop 

iLaws  of  1903,  chapter  43. 


The  Babcock  Test. 


47 


ACID  BOTTLtii 


cock  through  which  the  acid  passes  has  a  diameter  of  at 
least  one-eighth  of  an  inch,  as  is  generally  the  case.  We 
have  used  or  inspected  some  half  a 
dozen  other  devices,  which  have 
been  placed  on  the  market  by  vari- 
ous dealers  for  delivering  the  acid, 
but  cannot  recommend  them  for 
use  in  factories  or  outside  of  chem- 
ical laboratories. 

52.  Instead  of  measuring  out  the 
acid,  Bartlett  ^  suggested  adding  it 
directly  to  the  milk  in  the  test  bot- 
tles, till  the  mixture  rises  to  a  mark 
on  the  body  of  the  bottle  at  the 
point  where  this  will  hold  37.5  cc, 
i.  e.,  the  total  volume  of  milk  and 
acid  (89).  This  method  of  adding 
the  acid  is  in  the  line  of  simplicity, 
but  has  not  become  generally 
adopted.  If  the  method  is  used  the  marks  should  be  put 
on  by  the  manufacturers,  as  the  operator  in  attempting 
to  do  so  will  be  apt  to  weaken  or  break  the  bottles. 
Calibration  of  Glassware. 
Test  Bottles.  The  Babcock  milk  test  bottles  are  so 
constructed  that  the  scale  or  graduation  of  the  neck 
measures  a  volume  of  2  cubic  centimeters,  between  the 
zero  and  the  10  per  cent,  marks  (44).  The  correctness 
of  the  graduation  may  be  easily  ascertained  by  one  of  the 
following  methods: 

53.    (A.)    Calibration  with  mercury.      27.18  grams  of 
metallic  mercury  are  weighed  into  the  perfectly  clean 

1  Maine  experiment  station,  bull.  No.  31. 


Fig.  18.  Huedish  acid-bot- 
tle; the  side  tube  is  made 
to  hold  17.5  cc.  of  acid. 


48  Testing  Milk  and  Its  Products. 

and  dry  test  bottle.  Since  the  specific  gravity  of  mer- 
cury is  13.59,  double  this  quantity  will  occupy  a  volume 
of  exactly  2  cubic  centimeters  (48).  The  neck  of  the 
test  bottle  is  then  closed  with  a  small,  smooth  and  soft 
cork,  or  a  wad  of  absorbent  cotton,  cut  off  square  at  one 
end,  the  stopper  being  pressed  down  to  the  first  line  of 
the  graduation.  The  bottle  is  now  inverted  so  that  the 
mercury  will  run  into  its  neck.  If  the  total  space  in- 
cluded between  the  0  and  10  marks  is  just  filled  with  the 
two  cubic  centimeters  of  mercury,  the  graduation  is  cor- 
rect. Bottles,  the  whole  length  of  the  scale  of  which 
vary  more  than  two-tenths  of  one  per  cent.,  are  inaccu- 
rate and  should  not  be  used. 

The  mercury  may  be  conveniently  transferred  from  one 
test  bottle  to  another,  by  means  of  a  thin  rubber  tube 
which  is  slipped  over  the  end  of  the  necks  of  both  bot- 
,tles,  and  one  weighing  of  mercury  will  thus  suffice  for  a 
number  of  calibrations.  In  transferring  the  mercury, 
care  must  be  taken  that  none  of  it  is  lost,  and  that  small 
drops  of  mercury  are  not  left  sticking  to  the  walls  of  the 
bottle  emptied.  A  sharp  tap  on  the  bottle  with  a  lead 
pencil  will  help  to  remove  minute  drops  of  mercury  from 
the  inside.  Unless  the  bottles  to  be  calibrated  are  per- 
fectly clean  and  dry,  it  is  impossible  to  transfer  all  the 
mercury  from  one  bottle  to  another. 

After  several  calibrations  have  been  made,  the  mercury 
should  be  weighed  again  in  order  to  make  certain 
that  none  has  been  lost  by  the  various  manipulations. 
The  scales,  figs.  34  and  35,  shown  in  (91),  are  sufficiently 
delicate  for  making  these  weighings. 

54.  Cleaning  mercury.  Even  with  the  best  of  care, 
mercury  used  for  calibration  of  glassware  will  gradually 


The  Babcock  Test.  49 

become  dirty,  so  that  it  will  not  flow  freely  over  a  clean 
surface  of  glass.  It  may  be  cleaned  from  mechanical 
impurities,  dust,  films  of  grease,  water,  etc.,  by  filtration 
through  heavy  filter  paper.  This  is  folded  the  usual 
way,  placed  in  an  ordinary  glass  funnel  and  its  point 
perforated  with  a  couple  of  pin  holes.  The  mercury  will 
pass  through  in  fine  streams,  leaving  the  impurities  on 
the  filter  paper.  Mercury  may  be  freed  from  foreign 
metals,  zinc,  lead,  etc.,  sometimes  noticed  as  a  grayish, 
thin  film  on  its  surface,  by  leaving  it  in  contact  with 
common  nitric  acid  for  a  number  of  hours;  the  mercury 
is  best  placed  in  a  shallow  porcelain  or  granite  ware  dish 
and  the  nitric  acid  poured  over  it,  the  dish  being  covered 
to  keep  out  dust.  The  acid  solution  is  then  carefully 
poured  off  and  the  mercury  washed  with  water;  the  latter 
is  in  turn  poured  off,  and  the  last  traces  of  water  absorbed 
by  means  of  clean,  heavy  filter  paper. 

The  mercury  to  be  used  for  calibration  of  glassware 
should  be  kept  in  a  strong  bottle,  closed  by  an  ordinary 
stopper.  In  handling  mercury,  care  must  be  taken  not 
to  spill  any  portion  of  it;  finger- rings'should  be  removed 
when  calibrations  with  mercury  are  to  be  made. 

Mercury  forms  the  most  satisfactory  and  accurate  ma- 
terial for  calibration  of  test  bottles,  on  account  of  its 
heavy  weight  and  the  ease  with  which  it  may  be  manip- 
ulated. Equally  correct  results  may,  however,  with 
proper  care  be  obtained  by  using  water  for  the  calibration. 
(B.)  Calibration  with  water.  This  may  be  done  by 
means  of  a  delicate  pipette  or  burette,  or  by  weighing  in 
a  somewhat  similar  manner,  as  explained  in  case  of  cali- 
bration with  mercury. 
4 


50  Testing  Milk  and  Its  Products. 

55.  a,  Measuring  the  Water.  Fill  the  test  bottle  with 
water  to  the  zero  mark  of  the  scale;  remove  any  surplus 
water  and  dry  the  inside  of  the  neck  with  a  piece  of  filter 
paper  or  clean  blotting  paper;  then  measure  into  the 
bottle  2  CO.  of  water  from  an  accurate  pipette  or  burette, 
divided  to  g^,,  of  a  cubic  centimeter.  If  the  graduation 
is  correct,  2  cc.  will  fill  the  neck  exactly  to  the  10  per 
cent,  mark  of  the  scale. 

56.  b.  Weighing  the  water.  Fill  the  bottle  with  water 
to  the  zero  mark  of  the  scale  and  remove  any  surplus 
water  in  the  neck,  as  before.  Weigh  the  bottle  with  the 
water  contained  therein.  Now  fill  the  neck  with  water 
to  the  10  per  cent,  mark,  and  weigh  again.  The  differ- 
ence between  these  weights  should  be  2  grams. 

In  all  cases  when  calibrations  are  to  be  made,  the 
test  bottles,  or  other  glassware  to  be  calibrated,  must  be 
thoroughly  cleaned  beforehand  with  strong  sulfuric  acid 
or  soda  lye,  and  washed  repeatedly  with  pure  water, 
and  dried.  Glassware  is  not  clean  unless  water  will 
run  freely  over  its  surface,  without  leaving  any  ad- 
hering drops. 

57.  (C. )  The  Trowbridge  method  of  calibration.^  An 
extremely  simple  and  accurate  method  of  calibrating  test 
bottles  has  been  proposed  by  Mr.  O.  A.  Trowbridge  of 
Columbus,  Wis.  He  conceived  the  idea  of  measuring  the 
capacity  of  the  graduated  portion  of  the  neck  of  a  milk 
test  bottle  with  a  piece  of  metal  which  is  carefully  filed 
to  such  a  size  that  it  will  displace  exactly  two  cubic  centi- 
meters of  water.  He  used  a  thirty-penny  wire  nail,  cutting 
olf  the  head  of  the  nail  and  attaching  to  it  a  short  piece 

1  Hoard's  Dairyman,  Mar.  8,  1901,  by  De  Witt  Goodrich. 


The  Babcock  Test. 


51 


of  fine  wire,  either  looped  at  one  end,  as  sbown  in  fig.  19 
(A),  or  as  one  straight  piece  of  about  three  inches  long. 

The  wire  serves  as  a  handle  for  lowering  the  measure 
into  the  neck  of  the  test  bottles.  If  the  wire  is  attached 
as  shown  in  fig.  19  (A),  a  string  can  be  fastened  to  the 
loop  for  holding  the  measure  in  the  proper  place  in  the 
test  bottle. 

When  a  test  bottle  is  to  be  calibrated  by  this  standard 
measure,  it  is  filled  with  water  to   the   zero  mark  on  the 

Ineck    of    the     bottle.       The 
water  adhering  to   the   neck 
T^'  is     carefully    removed    with 

*  ■^'^  a    strip    of     blotting    paper, 

and  the  measure  (A)  is  then 
lowered  into  the  test  bottle, 
as  shown  in  (B),  to  the  point 
where  the  wire  loop  is  at- 
tached. If  the  water  rises 
from  0  to  10  on  the  neck 
when  the  point  of  the  meas- 
ure is  also  at  ten,  the  scale  is 
correct.  If  greater  varia- 
tions than  .2  of  one  per  cent, 
occur,  the  bottle  should  be 
rejected. 

The  figure  (C),  shows  one 
of  these  calibrators  made  in 
two  sections,  so  that  the  accu- 
racy of  the  5  as  well  as  the  10  mark  on  the  scale  may  be 
ascertained.  This  modification  was  proposed  by  Louis 
F.  Xafis&  Co.,  Chicago. 


1  ^ 


V 


B 


Fia  19.  (A)  Trowbridge  cali- 
brator as  used  in  test  bottle  (B), 
(Cj  Nafis  modification  of  (A). 


52  Testing  Milk  and  Its  Products. 

58.  The  standard  measure.  In  the  place  of  an  iron 
nail  a  piece  of  copper  or  glass  rod  may  be  advanta- 
geously used  as  a  standard  measure.  The  standardization 
is  most  conveniently  done  by  weighing.  Since  the  specific 
gravities  of  iron,  copper  and  glass  are  7.8,  8.9,  and  about 
2.7,  respectively,  pieces  of  these  materials  replacing  2  cc. 
of  a  liquid,  will  weigh  15.6,  17.8  and  5.4  grams,  for  iron, 
copper  and  glass  in  the  order  given. 

A  measure  of  the  right  weight  may  be  suspended  by  a 
very  fine  copper  or  platinum  wire  (melted  into  the  glass 
rod  if  this  material  be  chosen),  and  is  used  directly  for 
calibrating  test  bottles  as  described  above.  Before  a 
measure  so  made  is  used  as  a  standard,  its  accuracy 
should  be  determined  by  weighing  the  amount  of  water 
at  a  temperature  of  17.5°  C,  which  it  replaces.  The 
specific  gravity  of  glass  especiallj^,  varies  somewhat  ac- 
cording to  its  composition,  so  that  a  standardization  of  a 
measure  by  weight  alone  cannot  be  depended  upon  al- 
ways to  give  correct  results. 

59.  In  submerging  the  measure  in  the  test  bottle  to  be 
calibrated,  care  must  be  taken  that  all  air  bubbles  are 
removed  before  the  position  of  the  meniscus  of  the  water 
is  noted;  if  a  metal  standard  measure  is  used,  it  must  be 
kept  free  from  rust  or  tarnish. 

60.  Intermediate  divisions.  The  space  between  0  and 
10  on  the  scale  of  the  Babcock  test  bottle  is  divided  into 
50  divisions,  each  five  of  which,  as  previously  shown, 
representing  1  per  cent.  (44).  Since  these  intermediate 
divisions  are  generally  made  with  a  dividing  machine, 
they  are  as  a  rule  correct,  but  it  may  happen  that  the 
divisions  have  been  inaccurately  placed,  although  the 


The  BabcocJc  Test.  53 

space  between  0  the  10  is  correct.  The  accuracy  of  the 
intermediate  divisions  can  be  ascertained  by  sliding 
along  the  scale  a  strip  of  paper  upon  which  has  been 
marked  the  space  occupied  by  one  per  cent.,  and  com- 
paring the  space  with  those  of  e^^ch  per  cent,  on  tlie 
scale. 

61.  Calibration  of  skim  milk  test  bottles.  The  value  of 
each  division  on  the  skim  milk  bottles  is  one  twentieth 
of  one  per  cent.  (99);  there  are  ten  of  these  divisions 
or.  Ice.  in  the  whole  scale  which  shows  .5  per  cent, 
fat.  It  requires  very  careful  work  to  calibrate  this  scale 
and  it  is  best  done  by  weighing  the  amount  of  mercury 
which  will  just  fill  the  space  between  the  first  and  the 
last  divisions  (53);  the  correct  weight  of  this  mercury 
is  1.359  grams. 

62.  Calibrating  Cream  test  bottles.  The  cream  bottles 
may  be  calibrated  by  any  of  the  methods  given  for  milk 
bottles.  A'  cream  test  bottle  neck  that  measures  thirty 
per  cent,  fat  will  hold  6  cc,  and  6  grams  of  water  or 
81.54  grams  of  mercury. 

The  Trowbridge  method  of  calibrating  milk  test  bot- 
tles may  also  be  found  convenient  for  cream  bottles  and 
the  same  standard  measure  used.  The  part  of  the  scale 
from  0  to  10  being  calibrated  first,  then  from  10  to  20, 
and  from  20  to  30  per  cent,  in  the  same  way. 

63.  Pipette  and  acid  cylinder.  The  pipette  and  the 
acid  cylinder  used  in  the  Babcock  test  may  be  calibrated 
by  any  of  the  methods  already  given.  Sufficiently 
accurate  results  are  obtained  by  weighing  the  quantity 
of  water  which  each  of  these  pieces  of  apparatus  will 
hold,  viz.,  17.6  grams  and  17. 5 grams,  respectively.    The 


54  Testing  Milk  and  Ita  Products. 

necessity  of  previous  thorough  cleaning  of  the  glassware 
is  evident  from  what  has  been  said  in  the  preceding. 
The  pipette  and  the  acid  measure  may  be  weighed  empty 
and  then  again  when  filled  to  the  mark  with  pure  water, 
or  the  measure ful  of  water  may  be  emptied  into  a  small 
weighed  vessel,  and  this  weighed  a  second  time.  In 
either  case  the  weight  of  the  water  contained  in  the 
pipette  or  acid  measure  is  obtained  by  difference.^ 

Calibrations  of  the  acid  cylinder  are  generally  not 
called  for,  except  as  a  laboratory  exercise,  since  small 
variations  in  the  amount  of  acid  measured  out  do  not 
affect  the  accuracy  of  the  test. 

2. — Centeifugal  Machines. 

64.  The  capacity  of  the  testing  machine  to  be  selected 
should  be  governed  by  the  number  of  tests  which  are 
likely  to  be  made  at  one  time.  For  factory  purposes  a 
twenty-four  or  a  thirty-two  bottle  tester  is  large  enough, 
and  to  be  preferred  for  a  larger  tester,  even  if  toward  a 
hundred  samples  of  milk  are  to  be  tested  at  a  time.  The 
operator  can  use  his  time  more  economically  in  running 
a  machine  of  this  size  than  one  holding  fifty  or  sixty  bot- 
tles; the  work  of  filling  or  cleaning  the  bottles  and 
measuring  the  fat  can  be  done  while  the  tester  is  running 
if  a  double  supply  of  bottles  is  at  hand.  Large  testers 
require  more  power  than  smaller  ones,  and  when  sixty 
tests  are  made  at  a  time,  the  fat  column  in  many  bottles 


1 1  Cubic  centimeter  of  distilled  water  weighs  1  gram,  when  weighed  in 
a  vacuum  at  the  temperature  of  the  maximum  density  of  water  (4°  C);  for 
the  purpose  of  calibration  of  glassware  used  in  the  Babcock  test,  suf- 
ficiently accurate  results  are,  however,  obtained  by  weighing  the  water  in 
the  air  and  at  a  low  room  temperature  (60°  F.). 


The  BabcocTi  Test.  55 

will  get  cold,  before  the  operator  has  time  to  read  them, 
unless  special  precautions  are  taken  for  keeping  the  bot- 
tles warm. 

65.  The  tester  should  be  securely  fastened  to  a  solid 
foundation  and  set  so  that  the  revolving  wheel  is  level. 
The  latter  must  be  carefully  balanced  in  order  that  the 
tester  may  run  smoothly  at  full  speed  when  empty.  A 
machine  that  trembles  when  in  motion  is  neither  sat- 
isfactory nor  safe,  and  the  results  obtained  are  apt  to 
be  too  low.  High  standing  machines  are  more  apt  to 
cause  trouble  in  this  respect  than  low  machines,  and 
should  therefore  be  subjected  to  a  severe  test  before 
they  are  accepted. 

If  all  the  sockets  are  not  filled  with  bottles  when  a  test 
is  to  be  made,  the  bottles  must  be  placed  diametrically 
opposite  one  another  so  that  the  machine  will  be  balanced 
when  run.  The  bearings  should  be  kept  cleaned  and 
oiled  with  as  much  care  as  the  bearings  of  a  cream 
separator. 

The  cover  of  the  machine  should  always  be  kept  closed 
while  the  bottles  are  whirled,  and  should  not  be  removed 
until  the  machine  stops;  it  should  be  tight  fitting  and 
may  be  fastened  with  hooks  soldered  on  the  side  of 
the  machine;  test  bottles  sometimes  break  while  the 
machine  is  running  at  full  speed,  and  every  possible  pre- 
caution should  be  taken  to  protect  the  operator  from  any 
danger  from  spilled  acid  or  broken  glass. 

66.  Speed  required  for  the  complete  separation  of  the 
fat.  There  is  a  definite  relation  between  the  diameter  of 
the  Babcock  testers  and  the  speed  required  for  a  perfect 
separation  of  the  fat.     In  the  preliminary  work  with  the 


56  Testing  Milk  and  Its  Products. 

Babcock  test  the  inventor  found  that  with  the  machine 
used,  the  wheel  of  which  had  a  diameter  of  eighteen 
inches,  it  was  necessary  to  turn  the  crank,  so  as  to  give 
the  test  bottles  seven  or  eight  hundred  revolutions  per 
minute,  in  order  to  affect  a  maximum  separation  of  fat; 
later  work  has  shown  that  this  speed  is  ample,  Taking 
therefore  this  as  a  standard,  the  centrifugal  force  to  which 
the  contents  of  the  test  bottles  are  subjected  when  sup- 
ported on  an  eighteen -inch  wheel  and  turned  800  revolu- 
tions per  minute,  can  be  calculated  as  follows: 

The  centrifugal  force,  F,  acting  on  the  bottles  is  expressed  by 
the  formula 

^-^2:2? (I) 

in  which  w  =  the  weight  of  the  bottle  with  contents,  in  pounds; 
V  =  the  velocity,  in  feet  per  second,  and  r  -  the  radius  of  the 
wheel  in  feet. 

When  the  wheel  is  turned  800  times  a  minute,  a  bottle  sup- 
ported on  its  rim  will  travel  2;rrX%«oQ  =  2x3.1415  X  1^2  X«6«f  =62.83 
feet  per  second.  The  weight  of  a  bottle,  with  milk  and  acid,  is 
about  3  ounces,  or  j^g  of  a  pound.  Substituting  these  values 
for  v  and  w,  gives 

F  =  ^^=30.65Ibs. 

The  bottles  are  therefore,  under  the  conditions  given,  sub- 
jected to  a  pressure  of  about  30.65  pounds.  In  order  to  calculate 
the  speed  required  for  obtaining  this  force  in  case  of  machines 
of  other  diameters,  the  value  of  v  in  formula  (I)  is  found  from 


v=       /32.2  F  X  r  ^        ^        _        ^jj) 

1/  w 

Substituting  the  values  for  F  and  w, 

/82.2  X  30.65  r^/S^^i3^ 

y 

In  this  equation  the  values  r  =  5,  6,  7,  8,  9,  10,  11,  12  inches 
are  substituted  in  each  case  (-,|.  i^.^ij,   .   .   .    }  |  feet) ,  and  the 


The  Bahcoch  Test.  57 

velocity  in  feet  per  second  then  found  at  which  the  bottles  are 
whirled  when  placed  in  wheels  of  diameters  10  to  24  inches,  and 
subjected  in  each  case  to  a  centrifugal  force  of  30,65  lbs.     As  the 

number  of  revolutions  per  minute  =— _ -,  v  being  as  before 

2  TT  r 

the  velocity  in  feet  per  second,  and  r  the  radius  of  the  wheel, 
the  speed  at  which  the  wheel  must  be  turned,  is  found  by  sub- 
stituting for  V  the  values  obtained  in  the  preceding  calculations 
in  case  of  wheels  of  different  diameters.  The  results  of  these 
calculations  are  given  in  the  following  table: 

Diameter 
of  wheel,  D. 

10 
12 
14 

16 
18 
20 
22 
24 

These  figures  show  that  a  tester,  for  instance,  24  inches  in 
diameter,  requires  less  than  700  revolutions  per  minute  for  a 
perfect  separation  of  the  fat  in  Babcock  bottles,  while  a  ten- 
inch  tester  must  have  a  speed  of  nearly  1100  revolutions,  in 
order  to  obtain  the  same  result. 

The  speed  at  which  testers  of  different  diameters  should  be 
run  to  effect  a  complete  separation  has  been  calculated  by  Prof. 
C.  L.  Beach  in  the  following  manner. ^  The  same  standard  as 
before  is  taken,  viz.,  800  revolutions  for  an  18-inch  tester  (radius 
9 inches);  then  if  x  designate  the  radius  of  the  tester  and  y  the 
speed  required,  we  have 

xy -=9X8002,  or 


Velocity  in  feet 
per  second,  v. 

Number  of  revolutions 
of  wheel  per  minute. 

46.84 

ion 

51.31 

980 

55.43 

909 

59.26 

848 

62.84 

800 

66.24 

759 

69.47 

724 

72.56 

693 

/9   X   800^ 
^     V  X 

The  figures  obtained  by  the  use  of  this  formula  are  similar  to 
those  given  in  the  preceding  table. 


1  Private  communication. 


58  Testing  Milk  and  Its  Products. 

67.  To  liad  the  number  of  turns  of  the  handle  corres- 
ponding to  the  number  of  revolutions  made  by  the  wheel, 
the  handle  is  given  one  full  turn,  and  the  number  of 
times  which  a  certain  point  or  part  of  the  wheel  revolves, 
is  noted.  If  the  wheel  has  a  diameter  of  20  inches,  and 
revolves  12  times  for  one  turn  of  the  handle,  the  latter 
should  be  turned  yV  =^^  (see  table),  or  about  once  every 
second,  in  order  to  effect  a  maximum  separation  of  fat. 
By  counting  the  number  of  revolutions,  watch  in  hand, 
and  consulting  the  preceding  table,  the  operator  will 
soon  note  the  speed  which  must  be  maintained  in  case  of 
his  particular  machine.  It  is  vitally  important  that  the 
required  speed  be  always  kept  up;  if  through  careless- 
ness, worn-out  or  dry  bearings,  low  steam  pressure,  etc., 
the  speed  is  slackened,  the  results  obtained  will  be  too 
low;  it  may  be  a  few  tenths,  or  even  more  than  one  per 
cent.  Care  as  to  this  point  is  so  much  the  more  essen- 
tial, as  the  results  obtained  by  too  slow  whirling  may 
seem  to  be  all  right,  a  clear  separation  of  fat  being  often 
obtained  even  when  the  fat  is  not  completely  separated. 

68.  Ascertaining  the  necessary  speed  of  testers.  In 
buying  a  tester  the  operator  should  first  of  all  satisfy 
himself  at  what  speed  the  machine  must  be  run  to  give 
correct  results:  the  preceding  table  will  serve  as  a  guide 
on  this  point.  He  should  measure  out  a  dozen  tests  of 
the  same  sample  of  milk,  and  whirl  half  the  number  at 
the  speed  required  for  machines  of  the  diameter  of  his 
tester.  Whirl  the  other  half  at  a  somewhat  higher 
speed.  If  the  averages  of  the  two  sets  of  determinations 
are  the  same,  wi  bin  the  probable  error  of  the  test  (say, 
less  than  one-tenth  of  one  per  cent.)  the  first  whirling 


The  Babcock  Test.  59 

was  sufficient,  as  it  is  believed  will  generally  be  the  case. 
If  the  second  set  of  determinations  come  higher  than  the 
first  set;  the  first  whirling  was  too  slow,  and  a  new  series 
of  tests  of  the  same  sample  of  milk  should  be  made  to 
ascertain  that  the  second  whirling  was  ample. 

This  method  will  test  not  only  the  speed  required  with 
the  particular  machine  at  hand,  but  will  also  serve  to 
indicate  the  correctness  of  the  calibration  of  the  bottles. 
A  large  number  of  tests  of  the  same  sample  of  milk 
made  as  directed  (pouring  the  milk  once  or  twice  previ- 
ous to  taking  out  a  pipetteful  for  each  test)  should  not 
vary  more  than  two-tenths  of  one  per  cent,  at  the  outside, 
and  in  the  hands  of  a  skilled  operator  will  generally 
come  within  one -tenth  of  one  per  cent.  If  greater  dis- 
crepancies occur,  the  test  bottles  giving  too  high  or  too 
low  results  should  be  further  examined,  and  calibrated 
according  to  the  directions  already  given  (53  et  seq.). 

69.  Hand  testers.  When  only  a  few  tests  are  made  at 
a  time,  and  at  irregular  intervals,  as  in  case  of  dairymen 
who  test  single  cows  in  their  herds,  a  small  hand  tester 
answers  every  purpose.  These  may  be  had  in  sizes  from 
two  to  twelve  bottles.  In  selecting  a  particular  make  of 
tester  the  dairyman  has  the  choice  of  a  large  number  of 
difierent  kinds  of  machines.  It  is  a  source  of  regret  that 
most  of  the  early  machines  placed  on  the  market  for  this 
purpose  were  so  cheaply  and  poorly  constructed  as  to 
prove  very  unsatisfactory  after  having  been  in  use  for  a 
time.  The  competition  between  manufacturers  of  dairy 
supplies  and  the  clamor  of  dairymen  for  something 
cheap,  fully  accounted  for  this  condition  of  affairs.  This 
applies  especially  to  the  many  machines  made  with  belts 


60 


Testing  Milk  and 'Its  Products. 


or  friction  application  of  power.  The  main  objection  to 
such  machines  is  the  uncertainty  of  the  speed  obtained, 

when  they  have 
been  in  use  for 
some  time,  and 
the  belt  or  fric- 
tion appliance 
begins  to  slip. 
Hand  testers 
made  with  cog- 
geared  wheels 
are  more  to  be 
depended  on  for 
giving  the  nec- 
essary speed 
than  belt  or  fric- 

FiQ.21.    Type  of  Babcock  hand  testers.  ^.^^    machines; 

the  earlier  machines 
of  this  kind  were 
very  noisy,  but  at  the 
present  time  the  best 
machines  on  the  mar- 
ket are  of  this  type. 
These  are  provided 
with  spiral  cog- gear- 
ing and  ball  bearings, 
are  strongly  made  and 
will  run  smoothly  and 

without  noise  (figs.  21      ^ig.  22.    Type  of  Babcock  hand  testers. 

and  22  j;  in  cog-geared  machines  the  bottles  are  always 
whirled  at  the  speed  which  the  number  of  turns  made 
by  the  crank  would  indicate. 


The  Babcock  Test. 


61 


70 

bine 


,  Power  testers.  For  factory  purposes,  steam  tur- 
machiiies  (figs.  23-25)  are  most  satisfactory  when 
well  made  and  well  cared 
for.  They  should  always 
be  provided  with  a  speed 
indicator  and  steam 
gauge,  both  for  the  pur- 
pose of  knowing  that  suf- 


Fia.  23.    Type  of  Babcock  steam 
turbine  testers. 


Fig.  24.    Type  of  Babcock  steam  turbine  testers. 

ficient  speed  is  attained,  and  also  to  prevent  what  may 
be  serious  accidents  from  a  general  smash-up,  if  the  tur- 


62 


Testing  Miljc  and  Its  Products. 


bine  ''runs  wild"  by  turning  on  too  much  steam.  The 
revolving  wheel  of  the  tester  should  be  made  of  wrought 
or  malleable  iron,  or  of  wire,  so  that  it  will  not  be  broken 
by  the  centrifugal  force,  thus  avoiding  serious  accidents. 

The  swinging  pock- 
ets which  hold  the 
test  bottles  in  some 
machines,  should 
be  so  made  that  the 
bottles  will  not 
strike  the  center  of 
the  revolving 
frame  when  in  a 
horizontal  position. 
Tests  have  often 
been    lost    by   the 

FIG.  25.    Type  of  Babcock  turbine  testers.       ^^^    ^^    ^^^    ^^^^ 

catching  at  the  center,  the  bottles  thus  failing  to  take 
an  upright  position  when  the  whirling  stops. 

71.  The  exhaust  steam  pipe  of  turbine  testers  should 
not  have  too  many  turns  in  it  or  be  much  reduced  in  size 
from  that  of  the  opening  in  the  tester.  A  free  escape  of 
the  exhaust  steam  is  necessary  to  prevent  the  steam  col- 
lecting in  the  test  bottle  chamber  and  overheating  the 
test  bottle  when  whirled  (41). 

The  cover  of  the  tester  should  have  an  opening  pro- 
vided with  a  slidiug  damper  or  some  arrangement  by 
which  it  can  be  closed  when  desired.  If  whole  milk  or 
cream  is  being  tested,  this  hole  should  be  open  so  that  a 
draft  of  air  may  enter  the  test  bottle  chamber  during 
whirling,  and  force  the  steam  out  of  the  bottle  chamber 


The  Bahcock  Test.  63 

into  the  exhaust  pipe.  If  skim  milk  is  being  tested,  the 
opening  in  the  cover  should  be  closed.  This  shuts  off 
the  draft  of  air,  and  the  exhaust  steam  heats  the  test 
bottles  during  whirling  to  200°  F.  in  some  cases.  This 
high  temperature  aids  in  separating  the  last  traces  of  fat 
in  skim  milk  and  gives  a  most  accurate  test  of  samples 
containing  less  than  one-tenth  per  cent.  fat.  Some  of 
the  most  recent  makes  of  turbine  testers  are  provided 
with  holes  in  the  cover  and  dampers.  A  thermometer 
is  also  placed  in  the  cover. 

3.  —  Sulfuric  Acid. 

72.  The  sulfuric  acid  to  be  used  in  the  Babcock  test 
should  have  a  specific  gravity  of  1.82-1.83.^  The  com- 
mercial oil  of  vitriol  which  can  be  bought  for  about 
2  cents  a  pound  in  carboy  lots,  is  commonly  used.  One 
pound  of  acid  is  sufficient  for  fifteen  tests.  The  acid 
should  be  kept  in  stoppered  glass  bottles,  preferably 
glass  or  rubber  stoppered  ones,  since  a  cork  stopper  is 
soon  dissolved  by  the  acid  and  rendered  useless.  If  the 
bottle  is  left  uncorked  the  acid  will  absorb  moisture  from 
the  air  and  will  after  a  time  become  too  weak  for  use  in 
this  test.  Lead  is  the  only  common  metal  which  is  not 
dissolved  by  strong  sulfuric  acid;  where  considerable 
milk  testing  is  done,  it  is  therefore  desirable  to  provide 
a  table  covered  with  sheet  lead  on  which  the  acid  may 
be  handled. 


1 A  specific  gravity  of  1.82  means  that  a  given  volume  of  the  acid  weighs 
1.82  times  as  much  as  the  same  volume  of  Avater  at  the  same  temperature 
(see  also  under  Lactometer,  106) 


64  Testing  Milk  and  Its  Products. 

The  acid  dissolves  iroD,  tin,  wood  and  cloth,  and  burns 
the  skin.  If  acid  is  accidently  spilled,  plenty  of  water 
should  be  used  at  once  to  wash  it  off.  Ashes,  potash, 
soda,  and  ammonia  neutralize  the  action  of  the  acid,  and 
a  weak  solution  of  any  one  of  these  alkalies  can  be  used 
after  the  acid  has  been  washed  off  with  water.  The  red 
color  caused  by  the  action  of  the  acid  on  clothing  can  be 
removed  by  wetting  the  spot  with  weak  ammonia  water; 
the  ammonia  mu.>t,  however,  be  applied  while  the  stain 
is  fresh,  and  is  in  its  turn  washed  off  with  water. 

73.  Testing  the  strength  of  the  acid.  The  strength  of 
the  acid  can  be  easily  tested  by  the  use  of  such  a  balance 
as  shown  in  fig.  34  (91).  A  dry  test  bottle  is  weighed, 
and  then  filled  with  acid  exactly  to  the  zero  mark,  or  to 
any  other  particular  line  of  the  scale.  It  is  then  again 
weighed  accurately;  the  difference  between  these  two 
weights  will  give  the  weight  of  the  acid  in  the  bottle. 
INText  empty  the  bottle  and  rinse  it  thoroughly  with  water 
(until  the  water  has  no  longer  an  acid  taste):  fill  the 
bottle  with  water  to  the  same  line  as  before  and  weigh; 
the  difference  between  this  weight  and  that  of  the  empty 
bottle  gives  the  weight  of  the  same  volume  of  water  as 
that  of  the  acid  weighed.  Divide  the  weight  of  the  acid 
by  the  weight  of  the  water;  the  quotient  gives  the  spe- 
cific gravity  of  the  acid.  If  this  is  between  1.82  and 
1.83,  the  strength  of  the  acid  is  correct.  The  outside  of 
the  test  bottle  should  always  be  wiped  dry  before  the 
liquids  are  weighed  in  it.  Unless  great  care  is  taken  in 
measuring  out  the  acid  and  the  water,  and  in  weighing 
both  these  and  the  test  bottle,  the  results  obtained  will 
not  be  trustworthy. 


The  BabcocJc  Test  65 

74.  Too  strong  acid  can  sometimes  be  successfully  used 
by  taking  less  than  the  required  amount  of  each  test,  e.  g., 
about  15  cc.  Operators  are  warned  against  reducing  the 
strength  of  the  acid  by  adding  water  to  it,  as  accidents 
are  very  apt  to  occur  when  this  is  done.  A  too  strong 
acid  can,  if  desired,  be  weakened  by  simply  leaving  the 
bottle  uncorked  for  a  time,  or  by  pouring  the  acid  into  a 
bottle  containing  a  small  quantity  of  water.  In  the  lat- 
ter case  the  first  portions  of  acid  should  be  added  care- 
fully, a  little  at  a  time,  shaking  the  bottle  after  each 
addition,  so  as  not  to  cause  it  to  break  from  the  great 
heat  evolved  in  mixing  the  ^cid  and  the  water.  Never 
dilute  sulfuric  acid  by  pouring  water  into  it. 

75.  If  the  acid  is  too  weak,  correct  results  may  some- 
times be  obtained  by  using  more  than  the  specified 
quantity,  say  20  cc.  If  a  good  test  is  not  obtained  with 
this  quantity  of  acid,  a  new  lot  must  be  secured,  as  its 
specific  gravity  in  such  a  case  is  below  1.82.  The  ob- 
serving operator  will  soon  be  able  to  judge  of  the 
strength  of  the  acid  by  its  action  on  milk  in  mixing  the 
two  liquids  in  the  Babcock  test  bottles;  it  is  indeed  re- 
markable what  slight  differences  in  the  specific  gravity 
of  the  acid  will  make  themselves  apparent  in  working 
the  test;  as  regards  the  rapidity  with  which  both  the 
curdled  milk  is  dissolved  and  the  mixture  of  acid  and 
milk  turns  black. 

76.  Strength  of  sulfuric  acid.  The  relation  between 
the  strength  of  sulfuric  acid  and  its  specific  gravity  will 
be  seen  from  the  following  table : 


GG  Testing  Milk  and  Its  Products. 

Strength  of  Sulfuric  Acid  (Lunge  and  Tsler^  1890. ) 

Sulfuric  Acid  Specific  Gravity 

{HnSO, ).  {15°  C,  ualer  U°C). 

97  per  cent 1.841 

9G  "        1.840 

95  " 1.839 

94  "       1.837 

93  "        1  884 

92  "        1.830 

91  "       1.825 

90  "       1.820 

89  "        1.815 

88  " 1.808 

It  will  be  noticed  that  the  sulfuric  acid  to  be  used  in 

the  Babcock  test  should  contain  90  to  92  percent,  of  acid 

(H2SO4) ;  slightly  weaker  or  stronger  acid  than  this  may, 

as  previously  stated,  be  used  by  adjusting  the  quantity 

of  acid  taken  for  each  test  to  the  strength  of  the  acid, but 

successful  tests  cannot  be  made  with  acid  weaker  than 

89  per  cent,  or  stronger  than  95  per  cent. 

77.  The  Swedish  add  tester  is  a  small  hydrometer,  intended  to 
show  ^yhether  the  acid  to  be  used  in  the  Babcock  test  is  of  the 
correct  strength.  We  have  examined  a  number  of  these  testers, 
and  have  found  them  practically  useless  for  the  purpose  in- 
tended. The  reason  for  this  is  that  the  instrument  is  not  suffi- 
ciently sensitive;  while  the  testers  examined  were  found  to  sink 
to  the  line  marked  Correct  on  the  scale,  when  lowered  into  sul- 
furic acid  of  a  specific  gravity  of  1.83,  they  would  sink  to  a  point 
much  nearer  the  same  mark,  than  to  the  lines  marked  Too 
strong  or  Too  iveak,  respectively,  when  lowered  into  either  too 
strong  or  too  weak  acid. 

78.  The  color  of  the  fat  column  an  index  to  the  strength 
of  the  acid  used.  The  strength  of  the  acid  is  indicated 
to  a  certain  extent  by  the  color  of  the  fat  which  separates 
in  the  neck  of  the  test  bottle  when  milk  is  tested.  If  the 
directions  given  for  making  the  tests  are  carefully  fol- 
lowed, the  fat  separated  out  will  be  of  a  golden  yellow 


The  Babcock  Test  67 

color.  If  the  fat  is  light  colored  or  whitish,  it  generally 
indicates  that  the  acid'' is  too  weak,  and  a  dark  colored 
fat,  with  a  layer  of  black  material  beneath  it,  shows  that 
the  acid  is  too  strong,  provided  the  temperature  of  both 
milk  and  acid  is  about  70°.  [For  iuflnence  of  tempera- 
ture, see  next  paragraph.] 

The  strength  of  the  acid  used  in  the  test  is  not  suf- 
ficient at  ordinary  temperatures  of  testing  to  appreciably 
dissolve  the  fat,  but  a  variation  in  the  strength  of  the 
acid  or  in  the  temperature  of  the  milk  influences  the 
intensity  of  the  action  of  the  acid  on  the  fat,  as  shown  in 
the  color  of  the  fat  obtained. 

The  following  experiment  shows  the  relation  between 
the  strength  of  the  acid,  the  temperature  of  the  milk, 
and  the  color  of  the  fat: 

First:— Yvova  a  sample  of  milk  measure  the  usual  quantity 
for  testiug  into  each  of  three  bottles,  A,  B  aud  C.  Place  A  in 
ice  water,  and  C  iu  warm  water,  having  bottle  B  at  the  ordi- 
nary temperature.  After  the  bottles  have  been  left  for  ten  min- 
utes under  these  conditions,  add  the  normal  quantity  of  acid 
to  each  and  proceed  with  the  test  in  the  ordinary  manner. 

*S'eco?2f/.-— Measure  some  of  the  same  milk  into  three  other 
bottles,  D,  E  and  F.  Into  test  bottle  D  pour  the  usual  amount, 
of  rather  weak  acid;  add  the  same  amount  of  acid  of  normal 
streng:th  (1.82-1.88)  to  bottle  E,  and  add  17.5  cc.  of  a  still 
stronger  acid  (concentrated  sulfuric  acid,  sp.  gr.  1.84),  in  test 
bottle  F;  complete  these  tests  in  the  usual  way. 

On  the  completion  of  the  preceding  six  tests  the  operator  will 
notice  that  the  fat  in  the  necks  of  test  bottles  A  {cold  milk)  and 
D  {weak  acid)  is  much  lighter  colored  than  that  in  C  {warm 
milk)  and  F  {strong  acid),  and  that  the  color  of  the  fat  in  B 
{normal  temperature)  and  E  {normal  acid)  is  somewhere  be- 
tween that  of  these  two  series. 

79.  Influence  of  temperature  on  the  separation  of  fat. 

The  intensity  of  the  action  of  the  sulfuric  acid  on  the 


6S  Testing  MUk  and  Its  Products. 

milk  is  influenced  by  the  temperature  of  either  liquid; 
the  higher  the  temperature,  the  Tnore  intense  will  be  the 
action  of  the  acid  on  the  solids  of  the  milk.  It  may  be 
noticed  that  acid  from  the  same  carboy  will  act  differently 
on  milk  in  summer  than  in  winter  time,  if  the  acid  and 
the  milk  are  not  brought  to  a  temperature  of  about  70° 
before  testing  during  both  seasons.  The  temperature  of 
the  liquids  may  be  as  low  as  40°  F.  in  winter  and  as  high 
as  80°  F.  in  summer.  This  difference  of  forty  degrees 
will  often  have  considerable  influence  on  the  clearness  of 
the  fat  separated,  showing  white  curdy  substances  and  a 
light  colored  fat  in  winter,  or  black  flocculent  specks, 
with  a  dark  colored  column  of  fat  in  summer.  Both  these 
defects  can  be  avoided  when  the  acid  is  of  the  proper 
strength,  by  bringing  the  temperature  of  the  milk  and 
the  acid  to  about  70°  F.  before  the  milk  is  tested. 

The  operator  should  be  particularly  cautious  against 
over-heating  either  milk  or  acid;  so  intense  an  action 
may  be  caused  thereby  as  to  force  the  hot  acid  out  of  the 
neck  of  the  test  bottle  when  it  is  added  to  the  milk,  thus 
spoiling  the  test  and  possibly  causing  an  accident. 

4. — Water  to  be  used  in  the  Babcock  Test. 

80.  Eain  water,  condensed  steam,  or  soft  water  should 
be*  used  for  the  purpose  of  bringing  the  fat  into  the  neck 
of  the  test  bottles.  The  surface  of  the  fat  column  will 
then  usually  be  clear  and  distinct.  The  foam  or  bubbles 
that  sometimes  obscure  the  upper  line  (meniscus)  of  the 
fat,  making  indistinct  the  point  from  which  to  measure 
it,  is  generally  caused  by  the  action  of  the  acid  on  the 
carbonates  in  hard  water.     The  carbonic  acid  gas  liber- 


The  BabcocJc  Test.  69 

ated  from  hard  water  by  the  sulfuric  acid  is  more  or  less 
held  by  the  viscid  fat  and  produces  a  layer  of  foam  on 
its  surface.  If  clean  soft  water  cannot  be  obtained  for 
this  purpose,  hard  water  may  be  used  by  adding  a  few 
drops  of  sulfuric  acid  to  the  water  before  it  is  heated, 
thus  causing  the  carbonic  acid  to  be  driven  out  of  it. 
By  simply  boiling,  many  hard  waters  will  be  rendered 
soft  and  adapted  to  use  in  the  Babcock  test,  as  most  of 
the  carbonates  which  cause  this  foaming  are  thereby 
precipitated. 

If  the  test  has  been  completed,  and  a  layer  of  foam  ap- 
pears over  the  fat,  it  may  be  destroyed  by  adding  a  drop 
or  two  of  alcohol.  If  this  is  done,  the  fat  column  should 
be  read  at  once  after  the  alcohol  is  added,  as  the  latter 
will  soon  unite  with  the  fat  and  increase  its  volume. 

81.  Reservoir  for  water.  When  only  a  few  tests  are 
made  at  one  time,  the  hot  water  can  be  added  with  the 
17.6  cc.  pipette.  If  many  tests  are  made,  the  water  is 
more  conveniently  and  quickly  filled  into  the  test  bottles 
by  drawing  it  from  a  small  copper  reservoir  or  tin  pail 
suspended  over  the  testing  machine.^  The  flow  of 
water  through  a  rubber  tube  connected  with  the  reser- 
voir, is  regulated  by  means  of  a  pinch  cock.  The 
water  must  be  hot  when  added  to  the  test  bottles  so  as  to 
keep  the  fat  in  a  melted  condition  until  the  readings  are 
taken.  Most  turbine  testers  are  now  made  with  a 
very  convenient  water  reservoir  attached  to  the  tester 
(figs.   23-25). 


1  Ordinary  tinware  rusts  very  soon  when  water  is  left  standing  in  it, 
and  copper  reservoirs  are  therefore  more  economical. 


70 


Testing  Milk  and  Its  Products. 


The  use  of  zinc  or  steel  oilers,  or  perfection  oil  cans 
has  been  suggested,  as  a  handy  and  rapid  method  of 
adding  hot  water  to  the  test  bottles. 

5. — Modifications  of  the  Babcock  Test. 

82.  The  Russian  milk  test.  The  same  chemical  and 
mechanictil  principles  applied  in  the  regular  Babcock 


Fig.  26.    The  Kussian  test. 

test,  are  used  in  the  Eussian  milk  test,  except 
that  in  this  case  the  machine  in  which  the 
bottles  are  whirled,  and  the  bottles  them- 
selves, are  so  constructed  that  the  latter  can 
be  filled  with  hot  water  while  the  machine  is 
running  at  full  speed,  thus  saving  time  and 
trouble  incident  to  the  stopping  of  the  tester 
and  filling  the  bottles  by  means  of  a  pipette.  Test  bJttie 
The  milk- measuring  pipette  (fig.  28)  and  the  Russian  test. 
acid  measure  used  in  the  Russian  test  are  one-half  of  the 
ordinary  size,  and  the  test  bottles  are  made  in  two  pieces, 
with  a  detachable  narrow  graduated  stem  (see  fig.  27). 
The  machine  is  substantially  made  of  cast  iron;  it  is  pro- 


The  Babcock  Test. 


71 


vided  with  a  very  satisfactory  speed  indicator  which 
shows  at  any  time  the  number  of  revolutions  at  which 
the  bottles  are  being  turned.  The  accompanying  illus- 
trations show  the  apparatus  used  in  the  Rus- 
sian test.  When  the  directions  for  operating 
the  test  are  followed  closely,  the  results  ob- 
tained are  accurate  and  very  satisfactory. 

83.  Bartlett's  modification.  Bartlett'  pro 
posed  a  modification  of  the  method  of  pro- 
cedure in  the  Babcock  test,  which  aims  to 
simplify  the  manipulations.  20  cc.  of  acid 
are  added,  instead  of  17.5  cc,  and  the  bottles 
filled  with  the  milk-acid  mixture  are  left 
standing  for  not  less  than  five  minutes  and 
then  filled  with  hot  water  to  within  the  scale; 
the  bottles  are  then  whirled  for  five  minutes 
at  the  regular  rate  (52). 

In  the  experience  of  the  authors  the  modi- 
fication can  not  always  be  depended  upon  to 
give  satisfactory  results.  When  published  it 
was  tried  by  each  of  the  one  hundred  students  in  the 
Wisconsin  Dairy  School;  while  some  of  these  operators 
obtained  a  clear  separation  of  fat,  and  results  that  com- 
pared favorably  with  those  made  by  the  regular  Babcock 
test,  others  failed  to  obtain  correct  results  with  the 
method  as  modified.  It  is  not  known  that  the  modifica- 
tion has  proved  superior  to  or  taken  the  place  of  the 
regular  Babcock  test  to  any  extent.^ 


Fig.  28. 
Pipeite  used 
in   the  Rus- 
sian te.st. 


1  Maine  experiment  station,  Bull.  No.  31  (S  S.). 

2  The  German  dairy  chemist^iegfeld  in  18 )!»  proposed  a  modification  of  the 
Babcock  test(  Molkerri  Ztg.,  Hildesheini,  1899,  p.  51)  using  2  cc.  of  amy  1  alcohol 
with  the  sulfuric  acid,  and  filling  up  withdilutesulfuricacid(  1:1,  sp.gr.  1.5) 


72 


Testing  Milk  and  Its  Products. 


84.  Bausch  and  Lomb  centrifuge.  Fig.  29  shows  a 
form  of  hand  centrifuge  which  may  be  used  to  advantage 
by  physicians  or  in  a  pathological  laboratories  for  the 
determination  of  fat  in  milk.  The  centrifuge  is  espe- 
cially designed  for  examination  of  urine,  sputum,  blood, 
etc.,  but  has  been  adapted  to  milk  analysis  by  the  Leff- 

mann  &  Beam  test,  a  special 
form  of  bottle  (fig.  30)  having 
been  constructed  for  this  pur- 
pose. The  machine  gives  sat- 
isfactory results  by  the  Bab- 
cock  test  as  well,  provided 
the  acid  used  is  1.83-1.84,  or 
if  the  bottles  containing  the 

_      acid-milk   mixture 

be  placed  in  hot 
water  for  five  or  ten 
minutes  prior  to 
the  whirling.  As 
the  bottles  are  cali- 
brated  for   only  5 

Fig.  30.  Test 

bottle  for  cc.  of  milk  and  the 

ph  y  si«ian's 

centrifuge,     neck  of  the  bottles, 


f 


V 


Fig.  2t).    Physician's  centrifuge 
that  may  be  used  for  milk  testing 


with  scale,  is  correspondingly  fine,  testing  milk  with  this 
machine  requires  some  nicety  of  manipulation  not  called 
for  in  case  of  testers  constructed  for  the  use  of  farmers 
and  dairymen. 

in  one  filling,  in  placeof  water  after  the  whirling.  Aclear  separation  of  the 
fat  is  facilitated  by  both  these  changes,  but  when  properly  conducted  there 
is  no  difficulty  whatever  in  obtaining  a  clear  fat  column  in  the  Babcock  test 
as  described  in  this  book,  and  the  modification  will  not  therefore  be  likely 
to  be  introduced  in  American  factories.  It  has  become  quite  generally 
adopted  in  North  German  creameries  where  the  Babcock^test  isused. 


CHAPTER  ly. 

creah  testing. 

85.  Cream  may  be  tested  by  the  Babcock  test  in  the 
same  manner  as  milk,  and  the  results  obtained  are  accu- 
rate when  the  necessary  care  has  been  taken  in  sampling 
the  cream  and  measuring  the  fat.  The  composition  of 
cream  varies  greatly  according  to  the  process  of  cream- 
ing, temperature  of  milk  during  the  creaming,  quality 


Fig.  31. 
Students  testing  dairy  products 


and  composition  of  the  milk  to  be  creamed,  etc.  The 
cream  usually  met  with  in  separator  creameries  will  con- 
tain from  25  to  50  per  cent,  or  on  the  average  about  35 
per  cent,  of  fat.     Cream  from  hand  separators  may  be  as 


74  Testing  Milk  and  Its  Products. 

rich  as  this,  but  as  delivered  to  creameries  it  often  con- 
taios  onlj'  20  per  cent,  of  fat.  An  average  grade  of  market 
cream  as  retailed  contains  about  25  per  cent,  of  fat.  If  18 
grams  of  25  per  cent,  cream  is  measured  into  an  ordinary 
Babcock  test  bottle,  there  will  be  18 X. 25  =  4. 5  grams 
(or,  since  the  specific  gravity  of  butter  fat  is  about  .9, 
i^=5  cc. )  of  pure  butter  fat  in  the  bottle.  It  is  shown, 
however,  (p.  38),  that  the  space  from  0  to  10  in  the  neck 
of  these  bottles  holds  exactly  2  cc.  The  neck  of  the  milk 
test  bottles  will  not  be  large  enough  to  show  the  percent, 
of  fat  in  a  sample  of  cream  if  18  grams  are  taken  for  test- 
ing, and  it  is  therefore  necessary  to  adopt  special  meas- 
ures when  cream  is  to  be  tested. 

86.  Errors  of  measuring  cream.  Several  factors  tend 
to  render  inaccurate  the  measuring  of  cream  for  the  Bab- 
cock test,  and  correct  results  can  therefore  only  be  ob- 
tained by  weighing  the  cream.  If  a  17.6  cc.  pipette  is 
used  for  measuring  the  cream,  it  will  not  deliver  18 
grams  of  cream,  as  it  will  of  milk,  for  the  following 
reasons: 

1.  The  specific  gravity  of  cream  is  lower  than  that  of 
milk;  if  a  certain  quantity  of  milk  weighs  1030  lbs.,  the 
same  quantity  of  cream  will  weigh  from  1020  lbs.  to  be- 
low 1000  lbs.,  the  weight  being  determined  by  the  rich- 
ness of  the  cream;  the  more  fat  the  cream  contains,  the 
less  a  certain  quantity  of  it,  e.  g.,  a  gallon  will  weigh.' 

2.  Cream  is  thicker  (more  viscous)  than  milk  at  the 
same  temperatures,  and  more  of  it  will  adhere  to  the  sides 
of  the  measuring  pipette  than  in  case  of  milk.  This  is  of 
special  importance  in  testing  very  rich  or  sour  cream. 

1  For  specific  gravity  of  cream  of  different  richness,  see  table  on  p.  75. 


Cream  Testing.  75 

3.  In  case  of  separator  cream,  more  or  less  air  will 
become  incorporated  with  the  cream  during  the  process 
of  separation.  In  the  ripening  of  cream,  the  fermenta- 
tion gases  developed  are  held  in  the  cream  in  the  same 
way  as  bread  dough  holds  the  gases  generated  by  yeast. 
In  either  case  the  weight  of  a  certain  measure  of  cream 
is  diminished. 

87.  As  an  illustration  of  the  effect  of  the  preceding 
factors  on  the  amount  of  cream  measured  out  by  a  Bab- 
cock  17.6  cc.  pipette,  the  following  weighings  of  separ- 
ator cream  are  given  (column  h).  The  cream  was  in 
all  cases  fresh  from  the  separator;  it  was  weighed  as  de- 
livered by  the  pipette  into  a  cream  test  bottle  (91),  and 
the  test  proceeded  with  at  once;  the  specific  gravity  of 
the  cream  was  determined  by  means  of  a  picnometer, 
(247).  The  data  given  are  in  all  cases  averages  of  sev- 
eral determinations:  the  samples  of  cream  have  been 
grouped  according  to  their  average  fat  contents.^ 
Weiqht  of  fresh  separator  cream  delivered  by  a  17.6  cc.  pipette. 

Per  cent  sineeitio  uravHu  (17  '■p  C)  Weight  of  Cream  deliv- 

offatin  ^pecijic  gravity  i,i,  o    c;  ered,  grams. 

cream.  ^    '  ,                                      (6) 

10  1.023  17.9 

15  1.012  17.7 

20  1.008  17.3 

25  1.002  17.2 

30  .996  17.0 

35  .980  16.4 

40  .966  16.3 

45  .950  16.2 

50  .947  15.8 

The  figures  in  the  table  show  plainly  the  variations 
in  the  specific  gravity  of  cream  of  different  richness  and 


1  For  influence  of  condition  of  cream  on  the  amount  measured  out  with 
a  17  6cc.  pipette,  see  also  Bartlett,  Maine  exp.  sta.,  Bull,  31  (S.  S.). 


76  Testing  Milk  and  Its  Products. 

the  error  of  making  tests  of  cream  by  measuring  it  with 
a  17.6  cc.  pipette,  especially  if  the  pipette  is  not  rinsed 
and  the  washings  added  to  the  test  bottle;  if  the  cream 
to  be  sampled  is  fresh  separator  cream  testing  over  30 
per  cent,  less  than  17.0  grams  of  cream  will  be  delivered 
into  the  test  bottle,  and  the  results  of  the  reading  will 
be  at  least  one-eighteenth  too  low,  or  about  1.4  per  cent, 
on  a  25  per  cent,  cream.  If  the  cream  is  sour,  the  error 
will  of  course  be  still  greater. 

It  should  be  remembered  that  the  specific  gravities  of 
the  cream  given  in  the  table  refer  to  fresh  separator 
cream  only.  Considerable  air  is  incorporated  during  the 
separation,  and  cream  of  this  kind  is  therefore  lighter 
than  gravity  cream  of  corresponding  fat  contents. 

88.  Weighing  cream  for  testing.  For  the  reasons  stated 
in  the  preceding,  accurate  tests  of  cream  can  only  be 
made  by  weighing  the  cream  into  the  Babcock  test  bottles. 
This  is  recognized  by  a  law  passed  by  the  Wisconsin  leg- 
islature of  1903,  which  requires  cream  to  be  weighed  for 
testing  where  it  is  sold  on  the  basis  of  its  fat  content. ' 

The  simplest  method  is  to  weigh  9  or  18  grams  of  the 
sample  on  a  small  cream  weighing  scale  (see  p.  79)  into 
one  of  the  special  forms  of  cream-test  bottles. 

Cream  test  bottles.  Special  forms  of  bottles  have 
been  devised  for  testing  samples  of  cream  by  the  Bab- 
cock test  by  Bartlett  of  Maine,  Winton  of  Connecticut, 
and  by  various  manufacturers. 

89.  The  bulb-necked  cream  bottles  (fig.  32)  allow   the 


1  Chapter  43,  laws  of  1^03,  An  act  to  prescribe  the  standard  measures  for 
the  use  of  the  Babcock  test  in  determining  the  per  cent,  of  butter  fat  in 
milk  or  cream. 


Cream  Testing. 


77 


( 


testing  of  cream  containing  23  or  25  per  cent,  of  fat, 
when  the  usual  quantity  of  cream"  (18  grams)  is  taken. 
The  neck  is  graduated  from  0  to  23  per  cent., 
and  in  some  cases  to  25  per  cent.,  the  gradua- 
tion extending  both  below  and  above  the  bulb. 
This  is  sometimes  an  inconvenience,  as  the 
water  must  be  added  carefally  so  that  the 
lower  end  of  the  column  of  fat  will  always 
come  below  the  bulb,  in  the  graduated  part  of 
the  neck,  and  not  in  the  bulb  itself.  Espec- 
ially in  case  of  beginners,  tests  are  often  lost 
when  this  bottle  is  first  used,  for  the  reason 
given.  It  is  recommended  to  fill  these  bottles 
with  the  first  portion  of  hot  water  to  just  above 
the  bulb,  so  that  one  can  see  how  much  water 
to  add  the  second  time  in  order  to  bring  the 
fat  within  the  scale. 

Each  division  of  the  scale  on  these   cream 
bottles  represents  two-tenths  of  one  per  cent,  of 

,     ...  _,,  .       Fig.  32.  The 

fat  as  in  case  of  the  milk  test  bottles.      ihis  buib-necked 

'  cream  test 

form  of  bottle  is  no  longer  used  to  any  extent,  bottle. 
as  it  has  been  largely  replaced  by  the  cream-bottle  de- 
scribed in  the  following  paragraph. 

90.  The  Linton  cream  bottle.  The  cream  test  bottle 
devised  by  Winton,^  (fig.  33),  has  a  neck  of  the  usual 
length,  and  of  sufficient  width  to  measure  30  per  cent,  of 
fat.  The  scale  of  the  neck  is  divided  into  one-half  per 
cents.,  but  readings  of  a  quarter  of  a  per  cent,  can  easily 
be  estimated.     Determinations  of  fat  in  cream  accurate 


1  Connecticut  experiment  station  (New  Haven),  Bull.  No.  117;  report 
189J,  p.  224. 


Testing  Milk  and  Its  Products. 


to  a  quarter  of  a  per  cent,  are  sufficiently  exact  for  most 
commercial  purposes,  e.  g.,  in 
creameries,  and  this  form  of  cream 
bottle  will  be  found  very  convenient 
in  making  tests  of  composite  sam- 
ples of  cream. 

Cream  test  bottles  of  a  smaller 
bore,  similar  to  that  shown  in  fig. 
33,  are  greatly  to  be  preferred  to 
those  with  wide  necks,  since  they 
permit  of  accurate  readings  to  a 
quarter  of  a  per  cent. 

Other  forms  of  cream- test  bottles 
which  will  allow  the  testing  of  50-55 
per  cent,  cream  have  been  placed 
on  the  market  during  late  years 
by  some  manufacturers.  These  bot- 
tles have  very  long  necks  and  re- 
quire especially  constructed,  large 
and  deep  (and  therefore  costly) 
testers  (see  fig.  25).  It  does  not  ap- 
pear that  these  machines  or  accom- 
pany ingbottleshave  met  with  gener- 
al favor  among  creamery  operators. 

91.  Scales  for  weighing  the  cream. 
When  a  small,  delicate  balance  is 
used,  cream  can  be  weighed  rapidly 
into  the  bottles.  Either  of  the  scales 
shown  in  the  accompanying  illustra- 
tioils  (fig.  34-35),  will  be  found 
sufficiently  accurate  for  this  pur- 
pose; a  small  scale  of  this  kind  is  also  convenient  and 


Fig.  33.    The  cream 
test  bottle. 


Cream  Testing.  79 

helpful  iu  testing  cheese,  butter  and  condensed  milk, 
in  determining  the  strength  of  sulfuric  acid,  and  the 
accuracy  of  test  bottles  and  pipettes  (q.  v.)-  In 
testing  cream  by  weight,  the  test  bottle  is  first 
weighed  empty,  and  again  when  9  or  18  grams  of 
cream  have  been  placed  in  it;  the  difference  between  the 
two  weights  gives  the  weight  of  cream  taken  for  the  test. 
If  the  cream  contains  less  than  30  per  cent,  of  fat,  the 
regular  milk  test  bottle  can  be  used  for  testing  the 
cream,  if  not  much  more  than  5  grams  are  weighed  out; 


Fi(4.  3i  and  '60.  Scales  used  for  weighing  cream,  cheese,  etc.,  in  the 
Babcock  test. 

If  more  cream  is  taken,  or  if  this  is  richer  than  30  per 
cent.,  it  is  advisable  to  use  the  cream  bottle. 

The  cream  scale  shown  in  fig.  35  permits  the  weighing 
of  six  samples  of  cream  on  each  pan  with  only  one  taring 
of  the  bottles,  which  greatly  facilitates  the  work  of  test- 
ing the  cream. 

The  operator  should  be  careful  in  weighing  the  cream 
not  to  spill  it  on  the  outside  of  the  test  bottle.  If  less 
than  18  grams  of  cream  has  been  weighed  into  the  bottle, 
sufficient  water  is  added  to  the  bottle  to  make  the  total 
volume  about  18  cc.  The  usual  quantity  of  acid  (17.5  cc. ) 
is  then  added,  and  the  test  completed  in  the  ordinary 
manner.  The  reading  of  the  amount  of  fat  in  the  neck 
of  the  test  bottle  will  not  show  the  correct  per  cent,  of 


80  Testing  Milk  and  Its  Products. 

fat  in  the  cream,  unless  18  grams  were  weighed  out.  If 
less  than  18  grams  were  taken  the  per  cent,  of  fat  in  the 
cream  tested  is  obtained  by  multiplying  the  reading  by 
18,  and  dividing  the  product  by  the  weight  of  the  cream 
taken. 

Example:  Weight  of  cream  tested,  5.2  grams;  readingof  col- 
urna  of  fat  ^'9.8,  ->9.7,  average  9.75;  percent,  of  fat  in  the  cream 
9.75X18 


5.2 


=33.75. 


It  is  very  convenient  to  weigh  out  18  grams  of  cream 
(or  a  fraction  thereof)  so  that  the  readings  may  be  taken 
directly  from  the  neck  of  the  bottle.  The  smaller  the 
quantity  of  cream  taken  for  a  sample,  the  greater  is 
the  error  introduced  by  inaccurate  weighings  or  read- 
ings. The  reading  is  rendered  more  accurate  and  cer- 
tain if  a  number  of  tests  of  a  sample  are  made,  at  least 
two  or  three,  and  the  results  averaged. 

92.  Measuring  cream  for  testing.  Where  a  special 
cream  scale  or  a  small  balance  is  not  available,  fairly 
satisfactory  results  may  be  obtained  with  cream  of 
low  or  average  quality  by  measuring  out  the  sam- 
ple with  a  17.6  pipette  and  correcting  the  results  as 
indicated  below.  One  of  the  cream  testbottles  or  a 
common  milk  test  bottle  may  be  used  for  this  purpose.  The 
table  given  on  p.  75  shows  that  a  17.6  cc.  pipette, 
in  the  case  of  cream  containing  less  than  25  per  cent, 
fat  and  fresh  from  the  separator,  will  deliver  only 
17.2  grams  of  cream,  that  is,  the  results  will  be  ^'g'^  or 
.  44  per  cent,  too  low.  In  the  same  way  in  case  of  40 
per  cent,  cream  only  16.3  grams  of  cream  would  be  de- 
livered,   and   the   results   therefore   .94   per    cent,    too 


Oream  Testing.  81 

low.  When  the  cream  has  been  ripened  or  is  thick, 
less  cream  woald  be  deliv^ered  than  the  amounts 
given,  and  the  error  introduced  by  measuring  out 
the  samples  correspondingly  increased.  A  table  of 
correction  for  testing  such  cream  by  measuring  the  sam- 
ple has  been  prepared  by  Prof.  Eckles  of  Iowa  experi- 
ment station.  ^ 

Approximately  correct*  results  may  be  obtained  in 
testing  thin  cream  by  using  an  18  cc.  measuring  pipette; 
to  avoid  the  expense  and  trouble  of  using  two  different 
pipettes,  one  for  milk  and  one  for  cream,  a  pipette  with 
two  marks  on  the  stem,  at  17.6  cc.  and  18  cc,  has  been 
placed  on  the  market,  the  former  mark  being  used  when 
milk  is  tested,  and  the  latter  for  cream.'^ 

93.  Use  of  milk  test  bottles.  Cream  may  be  tested  by 
emptying  a  17.6  cc.  pipetteful  of  the  sample  into  two  or 
more  milk  test  bottles,  dividing  the  amount  about  equally 
between  the  bottles  and  filling  the  pipette  with  water  once 
or  twice,  which  is  then  in  turn  divided  about  equally 
between  the  test  bottles;  the  per  cent,  of  fat  in  the  cream 
is  found  by  adding  the  readings  obtained  in  each  of  the 
bottles.  Milk  and  water  must  be  mixed  before  the  acid 
is  added. 

This  method  does  away  with  the  error  incident  to  the 
adhesion  of  cream  to  the  side  of  the  pipette,  but  not  that 
due  to  the  low  specific  gravity  of  the  cream,  and  the  re- 
sults  obtained  will  therefore  be  too  low.     The  dilution  of 

1  Press  Bull,  dated  August,  1901. 

2  Professor  Spill  man,  in  Bull    32  of  Washington  experiment  station 
reconi mends  the  use  of  a  17  6  cc.  pipette  for  testing  cream,  the  results  ob- 
tained being  corrected  by  a  certain  per  cent.,  as  shown  in  a  table  given  in 
the  bulletin.    The  table  is  based  on  the  figures  given  on  p.  74  of  this  book 
and  is  therefore  only  applicable  to  fresh  separator  cream. 


82  Testing  Milk  and  Its  Products. 

the  cream  with  water  in  the  test  bottles  not  only  makes 
it  possible  to  bring  into  the  bottle  all  the  cream  measured 
out,  but  also  insures  a  clear  test.  If  ordinary  cream  is 
mixed  with  the  ordinary  quantity  of  sulfuric  acid  used  in 
the  Babcock  test,  a  dark-colored  fat  will  generally  be 
obtained,  while  the  cream  diluted  with  an  equal  or  twice 
its  volume  of  water,  when  mixed  with  the  ordinary  amount 
of  acid,  will  give  a  light  yellow*  clear  column  of  fat,  which 
will  allow  of  a  very  distinct  and  sharp  reading. 

The  number  of  bottles  to  be  used  for  testing  a  sample 
of  cream  by  this  method  must  be  regulated  by  the  rich- 
ness of  the  cream.  If  the  sample  probably  contains  20 
per  cent,  or  more,  a  pipetteful  should  be  divided  nearly 
equally  between  three  milk  test  bottles,  and  two-thirds 
of  a  pipetteful  of  water  is  added  to  each  bottle.  If  the 
cream  contains  less  than  20  per  cent,  of  fat,  it  will  only 
be  necessary  to  use  two  milk  test  bottles,  dividing  the 
pipetteful  between  these,  and  addingone  half  of  a  pipette- 
ful of  water  to  each  bottle. 

By  using  cream  test  bottles  (90),  more  accurate  tests 
may  be  obtained  in  case  of  cream  containing  as  much  as 
25  per  cent,  of  fat,  by  dividing  one  pipetteful  between 
two  bottles,  rinsing  half  a  pipette  of  water  into  each  one, 
than  by  adding  all  the  cream  to  one  bottle  without  rins- 
ing the  pipette,  for  reasons  apparent  from  what  has  been 
said  in  the  preceding. 

94.  Use  of  a  5  cc.  pipette.  When  the  cream  is  in  good 
condition  for  sampling,  satisfactory  results  can  be  ob- 
tained by  the  use  of  a  5  cc.  pipette,  provided  great  care 
is  taken  in  mixing  the  cream  before  sampling;  5  cc.  of 
cream  are   measured   into  a  milk   test   bottle,  and  two 


Cream  Testing. 


83 


pipettefuls  of  water  are  added.  Iruthis  way  all  the  cream 
in  the  pipette  is  easily  rinsed  into  tbe  test  bottle.  The 
readings  multiplied  by  ^=3.6  will  give  the  per  cent,  of 
fat  in  the  cream.  If  the  specific  gravity  of  the  cream 
tested  varies  appreciably  from  1,  corrections  should  be 
made  accordingly;  e.  g.,  if  the  specific  gravity  is  1.02; 
the  factor  shouldread^=3.53;  if  .95,  ,^=3.79,  etc. 

95.  Proper  readings  of  cream  tests.  The  accompanying 
illustration  (fig.  36),  shows  the  proper  method  of  read- 
ing the  fat  column  in  cream  tests;  read- 
ings are  taken  from  a  to  hy  not  to  d  or  to  c.  ^ 
No  special  precautiocs  other  than 
those  required  in  testing  milk  have  been 
found  necessary  in  testing  cream,  ex- 
cept that  it  is  sometimes  advisable  not 
to  whirl  the  test  bottles  in  the  cen- 
trifuge at  once  after  mixing,  but  to  let 
the  cream-acid  mixture  stand  for  a  while, 
until  it  turns  dark  colored.  At  first, 
the  mixture  of  cream  and  acid  is  much 
lighter  colored  than  that  of  milk  and 
acid,  owing  to  the  smaller  amount  of 
solids  not  fat  contained  in  the  cream. 
The  liquid  beneath  the  fat  in   a  com- 

Measur-  ^ 

in^thT  ifcr^Ta  pleted  test  ofcream  is  sometimes  milky  and 
fi^l^CuidbemTde  the  fat  appears  white  and  cloudy,  making 
from  a  to  b,  not  to  a  ^^  ^^^^^  reading  difficult.     Such  defects 

can  usually  be  overcome  by  placing  the  test  bottles  in  hot 
water  for  about  ten  minutes  previous  to  the  whirling,  or 


1  The  size  of  the  meniscus  is  magnified  in  the  cut. 


84  Testing  Milk  and  Its  Products. 

by  allowing  the  fat  to  crystalize  (which  is  done  by  cool- 
ing the  bottles  in  cold  water  after  the  last  whirling)  and 
remelting  it  by  placing  the  bottles  in  hot  water. 

96.  The  error  due  to  the  expansion  of  the  fat  in  case 
of  excessively  hot  turbine  testers  having  no  openings  in 
the  cover  as  mentioned  on  p.  36,  is  especially  noticeable 
in  cream  testing,  where  it  may  amount  to  one  per  cent, 
or  more.  In  order  to  obtain  correct  results  with  such 
testers,  the  hot  cream  test  bottles  must  be  placed  in 
water  at  about  140°  F.  for  a  few  minutes  before  the 
results  are  read  off. 


CHAPTER  y. 
BABCOCK  TEST  FOR  OTHER  MILK  PRODUCTS. 
97.  Skim  milk.     Each  division  on  the  scale  of  the  neck 
of  the  regular  Babcock  test  bottle  represents  two-tenths  of 
one  per  cent.  (44).  Whenasampleof  skim  milk  or  butter 
milk  containing  less  than  this  per  cent,  of  fat  is  tested,  the 
estimated  amount  is  expressed  by  different  operators  as 
one-tenth,     a  trace,    one-tenth    trace,    or   one   to  five- 
hundredths   of    one  per   cent.      Gravimetric   chemical 
analyses  of  skim  milk  have  shown  that  samples  which 
give  only  a  few  small  drops  of  fat  floating  on  the  water 
in  the  neck  of  the  test  bottle,  or  adhering  to  the  side  of 
the  neck,  generally  contain  one-tenth  of  one  per  cent,  of 
fat,  and  often  more.     Samples  of  skim  milk  containing 
less  than  one-tenth  of  one  per  cent,  of  fat  are  very  rare 
and  it  is  doubtful  whether  a  sample  of  separator  skim 
milk  representing  a  full  run  of,  say  5,000  lbs.  of  milk,  has 
ever  shown  less  than  five-hundredths  of  one  per  cent,  of 
fat.     Under  ordinary  factory  conditions,  few  separators 
will  deliver  skim  milk  containing  under  one- tenth  of  one 
per  cent,  of  fat,  when  the  sample  is  taken  from  the  whole 
day's  run.     This  must  be  considered  a  most  satisfactory 
separation.  ^ 

98.  The  reason  why  the  Babcock  test  fails  to  show  all 
the  fat  present  in  skim  milk  must  be  sought  in  one  or 
two  causes:  a  trace  of  fat  may  be  dissolved  in  the  sulfuric 
acid,  or  owing  to  the  minuteness  of  the  fat  globules  of 

1  For  comparative  analyses  of  separator  skim  milk  by  the  gravimetric 
method  and  by  the  Babcock  test,  see  Wis.  exp.  station  bull.  52  and  rep 
XVII,  p.  81;  see  also  Woll,  Testing  skim  milk  by  Babcock  test,  in  C<yuntry 
Gentleman,  April  26,  1902. 


86  Testing  Milk  and  Its  Products. 

such  milk  they  may  not  be  brought  together  in  the  neck 
of  the  bottles  at  the  speed  used  with  the  Babcock  test. 
The  latter  cause  is  the  more  likely  explanation.  If  a  drop 
of  the  dark  liquid  obtained  in  a  Babcock  bottle  from  a 
test  of  whole  milk,  be  placed  on  a  slide  under  the  micro- 
scope, it  will  be  seen  that  a  fair  number  of  very  minute 
fat  globules  are  found  in  the  liquid.  These  globules  are 
not  brought  into  the  column  of  fat  in  the  neck  of  the  bottle 
by  the  centrifugal  force  exerted  in  the  Babcock  test,  unless 
the  bottles  are  whirled  in  a  turbine  tester  in  which  they 
are  heated  to  200°  F.  or  higher,  (see  71) ;  the  loss  of  the  fat 
contained  in  these  fine  globules  is  compensated  for,  in  the 
testing  of  whole  milk,  by  a  liberal  reading  of  the  column 
of  fat  separated  out,  the  reading  being  taken  from  the 
lower  meniscus  of  the  fat  to  the  top  of  the  upper  one  (see 
p.  35) ;  in  some  separator  skim  milk,  on  the  other  hand,  not 
enough  fat  remains  to  completely  fill  the  neck,  and  the  ap- 
parent result  of  the  reading  must  therefore  be  increased 
by  from  five-hundredths  to  one-tenth  of  one  per  cent. 

It  follows  from  what  has  been  said  that  tests  of  skim 
milk  showing  no  fat  in  the  neck  of  the  test  bottles  on 
completion  of  the  test,  generally  indicate  inefficient  work 
of  the  centrifugal  tester  or  of  the  operator,  or  of  both. 
The  test  should  be  repeated  in  such  cases,  using  more  acid 
and  whirling  for  full  five  minutes.  Separator  skim  milk 
should  be  allowed  to  stand  10  to  15  minutes  for  the  air 
to  escape  before  the  sample  is  taken. 

In  order  to  bring  as  much  fat  as  possible  into  the  neck 
of  the  bottles  in  testing  skim  milk,  it  is  advisable  to  add 
somewhat  more  acid  than  when  whole  milk  is  tested,  viz., 
about  20  cc,  and  to  whirl  the  bottles  at  full  speed  for  at 


Babcock  Test  for  other  Mill-  Products. 


87 


least  five  minutes,  keeping  the  tester  as  hot  as  possible 
the  whole  time.^  The  readings  must  be  taken  as  soon  as 
the  whirling  is  completed,  as  owing  to  the  contraction 
of  the  liquid  by  cooling,  the  fat  otherwise 
adheres  to  the  inside  of  the  neck  of  the  test 
bottle  as  a  film  of  grease  which  cannot  be 
measured  by  the  scale. 

99.  The  double-necked  test  bottle,  (fig. 
37),  suggested  by  one  of  us,  ~  is  made  espe- 
cially for  measuring  small  quantities  of  fat 
and  gives  most  satisfactory  results  in  testing 
skim  milk  and  butter  milk.  Each  division 
of  the  scale  in  these  bottles  represents  five- 
hundredths  of  one  per  cent.,  and  the  marks 
are  so  far  apart  that  the  small  fat  column 
can  be  easily  estimated  to  single  hundredths 
of  one  per  cent.  In  the  first  forms,  now 
out  of  use,  the  neck  was  graduated  to  hun- 
dredths of  one  per  cent. 

The  value  of  the  divisions  of  the  scale  on 
the  double- necked  test  bottles  has  been  a 
subject  of  considerable  discussion,  and  vari- 


FiG.  87.    The 

double-neck  ed 

skim  milk  bot- 

.     ,  ,  ,  ^       ,       ,  tie    (sometimes 

ous  opinions  have  been  expressed  whether  (aiied  the  ohi- 

son  or  B.  &  W. 

they  show  one- tenth  or  one- twentieth  (.05)  bottle  ) 
of  one  per  cent,  of  fat.  By  calibration  with  mercury  the 
value  of  the  divisions  will  be  found  to  be  .05  or  one- 
twentieth  of  one  per  cent.,  but  as  shown  above,  the 
results  obtained  in  using  the  bottles  for  thin  separator 
skim  milk  often  come  at  least  .05  per  cent,  too  low,  so 
that,  practically  speaking,  each  division  maybe  taken  to 


1  See  Wis.  exp.  station,  report  XVII,  p.  81. 

2  Farrington,  and  first  constructed  by  Mr.  J .  J.  Nussbaumer,  of  Illinois 


88 


Testing  Milk  and  Its  Products. 


show  one  tenth  of  one  per  cent.,  if  the  fat  fills  only  one 
division  of  the  scale  or  less.^ 

The  double- necked  bottle  is  very  convenient  for  the 
testing  of  separator  skim  milk,  thin  butter  milk  and 
whey.  The  milk,  acid  and  water  are  added  to  the  bottle 
through  the  large  side-tube;  the  mixing  of  milk  and  acid 
must  be  done  with  great  care,  so  that  none  of  the  con- 
tents is  forced  into  the  line  measuring  tube  and  lost;  it  is 
best  to  add  half  of  the  acid  first  and  mix  it  with  the  milk, 
^r>^  and  then  add  the  rest.     When  the  fat  is 

in  the  lower  end  of  the  measuring  tube, 
it  can  be  forced  into  the  scale  by  pressing 
with  the  finger  on  the  top  of  the  side  tube. 
In  placing  the  double  necked  bottle  in 
the  tester  they  should  be  put  with  the 
filling  tube  toward   the  center  so  as  to 
avoid  any  of  the  fat  being  caught  be- 
tween this  tube  and  the  side  of  the  bot- 
tle when  it  resumes  a  vertical  position. 
This  test  bottle  is  more  fragile  and  ex- 
pensive than  the  ordinary  Babcock  bot- 
tles, and  must  be  carefully  handled;  it 
has  recently  been  made  of  heavier  glass 
FiG.38.  The  Wagner  a^d  ^his  form    is    to   be  highly  rccom- 
skim  milk  bottle,  mended.' 

100.  The  double-sized  skim  milk  bottle  is  of  no  particular 
value.     It  is  difficult  to  obtain  a  thorough  mixture  of 


M 


1  Wis.  experiment  station,  bull.  52;  Penna.  experiment  station,  report 
1896,  p.  221. 

2  A  copper  double-necked  test  bottle  with  a  detachable  graduated  glass 
neck  was  designed  and  tried  by  one  of  us  (F.)  a  lew  years  ago,  but  no 
special  advantages  over  the  glass  bottle  was  found  for  it. 


Babcock  Test  for  other  Milk  Products.  89 

the  milk  and  the  acid  in  these  bottles,  and  the  tests 
invariably  come  too  low,  more  so  than  with  the  regular 
Babcock  bottles  or  the  double- necked  skim  milk  bottles, 
for  reasons  that  are  readily  seen. 

lOr.  Buttermilk  and  whey.  The  testing  of  buttermilk  or 
lohey  by  the  Babcock  test  offers  no  special  difficulties,  and 
what  has  been  said  in  regard  to  tests  of  separator  skim 
milk  is  equally  true  in  case  of  these  by-products.  Whey 
contains  only  a  small  quantity  of  solids  not  fat,  viz.,  less 
than  7  per  cent.  (27),  and  the  mixing  with  acid  and  the 
solution  of  the  whey  solids  therein  is  therefore  readily 
accomplished;  the  acid  solution  is  of  a  light  reddish  color, 
turning  black  but  very  slowly. 

102.  Cheese.  Cheese  can  be  easily  tested  by  the  Bab- 
cock test  if  a  small  scale  (fig.  34)  is  at  hand  for  weighing 
the  sample;  the  results  obtained  will  furnish  accurate 
information  as  to  the  amount  of  fat  in  the  cheese,  provided 
good  judgment  and  exactness  are  used  in  sampling  and 
weighing  the  cheese.  The  following  method  of  sampling 
cheese  is  recommended:  ^ 

''  Where  the  cheese  can  be  cut,  a  narrow  wedge  reach- 
ing from  the  edge  to  the  center  of  the  cheese  will  more 
nearly  represent  the  average  composition  of  the  cheese 
than  any  other  sample.  This  may  be  cut  quite  fine,  with 
care  to  avoid  evaporation  of  water,  and  the  portion  for 
analysis  taken  from  the  mixed  mass.  When  the  sample 
is  taken  with  a  cheese  trier,  a  plug  taken  perpendicular 
to  the  surface,  one-third  of  the  distance  from  the  edge  to 
the  center  of  the  cheese,  will  more  nearly  represent  the 
average  composition  than  any  other.     The  plug  should 

1  U.  S.  Dept.  of  Agriculture,  Chemical  Divison,  bull.  No.  46,  p.  37. 


90  Testing  Milk  and  Its  Products. 

either  reach  entirely  through  or  only  half  way  through 
the  cheese. 

''  For  inspection  purposes  the  rind  may  be  rejected,  but 
for  investigations,  where  the  absolute  quantity  of  fat  in 
the  cheese  is  required,  the  rind  should  be  included  in  the 
sample.  It  is  well,  when  admissible,  to  take  two  or  three 
plugs  on  different  sides  of  the  cheese  and  after  splitting 
them  lengthwise  with  a  sharp  knife,  take  poitions  of  each 
for  the  test. ' ' 

103.  When  a  satisfactory  sample  of  the  cheese  has  been 
obtained,  about  5  grams  are  weighed  into  a  milk  test 
bottle,  or  a  larger  quantity  may  be  used  with  a  cream 
test  bottle.'  The  test  bottle  is  first  weighed  empty,  and 
again  after  the  pieces  of  cheese  have  been  added.  About 
15  cc.  of  warm  water  is  added  to  the  cheese  in  the  test 
bottle,  and  this  is  shaken  occasionally  until  the  cheese 
softens  and  forms  a  creamy  emulsion  with  the  water. 
A  few  cc.  of  acid  will  aid  in  this  mixing  and  disintegra- 
tion, the  process  being  hastened  by  placing  the  bottles 
in  tepid  water.  When  all  lumps  of  cheese  have  disap- 
peared in  the  liquid,  -the  full  amount  of  acid  is  added, 
and  the  test  completed  in  the  ordinary  manner. 

The  per  cent,  of  fat  in  the  cheese  is  obtained  by  multi- 
plying the  reading  of  the  fat  column  by  18  and  dividing 
the  product  by  the  weight  of  cheese  added  to  the  test 
bottle.  The  weighing  of  the  cheese  and  the  reading  of 
the  fat  must  be  done  with  great  care,  since  any  error 
introduced  is  more  than  trebled  in  calculating  the  per 
cent,  of  fat  in  the  cheese. 

104.  Condensed  milk.  The  per  cent,  of  fat  in  un- 
tweetened  condensed  milk  can  be  obtained  by  weighing 


BabcocJc  Test  for  other  Milk  Products.  91 

8  grams  into  a  test  bottle  and  proceeding  in  exactly  the 
same  way  as  given  under  testing  of  cheese.  It  is  not 
necessary  to  warm  the  condensed  milk  in  the  test  bottles, 
since  the  solution  of  this  in  water  is  readily  effected. 
Enough  water  should  be  added  to  make  the  total  volume 
of  liquid  in  the  bottles  15  to  18  cc. 

If  a  scale  is  not  available  for  weighing  the  sample, 
fairly  accurate  results  may  be  obtained  by  dilating  the 
condensed  milk  with  water  (1:3),  and  completing  the 
test  in  the  ordinary  manner.  When  this  is  done,  the  re- 
sults must  be  corrected  for  the  dilution  which  the  sample 
received. 

105.  Sweetened  condensed  milk.  The  testing  of  sweet- 
ened condensed  milk  presents  peculiar  difficulties, 
whether  it  is  to  be  tested  by  the  Babcock  test  or  by  chem- 
ical analysis.  It  may,  however,  be  readily  tested  by  the 
Babcock  test  by  introducing  certain  changes  in  the  manip- 
ulation of  the  test  as  worked  out  by  one  of  us  (F).^  A 
brief  description  of  the  manipulations  adopted  is  here 
given. 

About  sixty  grams  of  condensed  milk  are  weighed 
into  a  200  cc.  graduated  flask,  to  this  100  cc.  of  water 
are  added  and  the  solution  of  the  condensed  milk 
effected.  *The  flask  is  then  filled  to  the  mark  with 
water  and  after  mixing  thoroughly,  a  17.6  cc.  pipette  full 
is  measured  into  a  Babcock  test  bottle.  About  three  cc. 
of  the  sulfuric  acid  commonly  used  for  testing  milk  are 
then  added  and  the  milk  and  acid  mixed  by  shaking  the 
bottle  vigorously.  The  milk  is  curdled  by  the  acid,  and 
make  this  separation  complete  and  to  compact  the  curd 

1  Wis.  expt.  station,  report  XVI r,  pp.  86-89. 


92  Testing  Milk  and  Its  Products. 

the  curd  and  whey  separated  somewhat.  In  order  to 
into  a  firm  lump,  the  test  bottle  is  whirled  for  about  six 
minutes  at  a  rather  high  speed  (1,000  rev.)  in  a  steam- 
heated  turbine  centrifuge. 

The  chamber  in  which  the  bottles  are  whirled  ought 
to  be  heated  to  about  200°  F.  This  can  be  done  either 
by  the  turbine  exhaust  steam  which  leaks  into  the  test- 
bottle  chamber  of  some  machines,  or  by  means  of  a  valve 
and  pipe  which  will  allow  steam  to  be  turned  directly 
into  the  test  bottle  chamber.  After  this  first  whirling 
the  test  bottles  are  taken  from  the  centrifuge  and  by  be- 
ing careful  not  to  break  the  lump  of  curd  nearly  all  the 
whey  or  sugar  solution  can  be  poured  out  of  the  neck. 
Ten  cc.  of  water  are  then  poured  into  the  test  bottle  and 
the  curd  is  shaken  up  with  it  so  as  to  wash  out  more  of 
the  sugar.  Three  cc.  of  acid  are  now  added  as  before 
and  the  test  bottle  whirled  a  second  time  in  the  centri- 
fuge. The  whey  is  decanted  again  and  this  second  wash- 
ing removes  so  much  of  the  sugar  that  what  remains  will 
not  interfere  with  testing  in  the  usual  way.  The  curd  re- 
maining in  the  test  bottle  after  the  second  washing  is 
shaken  up  with  ten  cc.  of  water  and  to  this  water- emul- 
sion of  the  curd  the  usual  amount,  17.5  cc,  of  sulfuric 
acid  is  added  and  the  test  completed  in  the  same  way  as 
milk  is  tested.  The  amount  of  fat  finally  obtained  in  the 
neck  of  the  test  bottle  is  calculated  to  the  weight  of  con- 
densed milk  taken. 


CHAPTER  VI. 
THE  LACTOMETER  AND  ITS  APPLICATION. 

106.  The  Ouevenne  lactometer.  This  instrument  (see 
fig.  39,  next  page)  consists  of  a  hollow  glass  cylinder 
weighted  by  means  of  mercury  or  fine  shot  so  that  it  will 
float  in  milk  in  an  upright  position,  and  provided  with  a 
narrow  stem  at  its  upper  end,  inside  of  which  is  found  a 
graduated  paper  scale.  In  the  better  forms,  like  the  Que- 
venne  lactometer  shown  in  the  figure,  a  thermometer  is 
melted  into  the  cylinder,  with  its  bulb  at  the  lower  end 
of  the  lactometer  and  its  stem  rising  above  the  lactometer 
scale. 

The  lactometer  is  used  for  the  determination  of  the 
specific  gravity  of  milk.  The  term  specific  gravity  means 
the  weight  of  a  certain  volume  of  a  solid  or  a  liquid  sub- 
stance compared  with  the  weight  of  the  same  volume  of 
water  at  4°  C.  (39.2°  Fahr.);  for  gases  the  standard  of 
comi3arison  is  air  or  hydrogen.  If  the  milk  which  a  can 
will  hold  weighs  exactly  103.2  lbs.,  this  can  will  hold  a 
smaller  weight  of  water,  say  100  lbs. ,  as  milk  is  heavier 
than  water;  the  specific  gravity  of  this  milk  will  then 
be  ^f^  =1.032. 

The  specific  gravity  of  normal  cows'  milk  will  vary  in 
different  samples  between  1.029  and  1.035  a^ 60°  F.,  the 
average  being  about  1.032^^ 

107.  The  lactometer  enables  us  to  determine  rapidly 
the  relative  weight  of  milk  and  water.  Its  application 
rests  on  well-known  laws  of  physics:  When  a  body 
floats  in   a   liquid,  the  weight  of  the  amount  of  liquid 


94 


Testing  Milk  and  Its  Products. 


which  it  replaces  is  equal  to  the  weight 
of  the  body.  It  will  siak  further  into  a 
light  liquid  than  into  a  heavy  one,  be- 
cause a  larger  volume  of  the  former  will 
be  required  to  equal  the  weight  of  the 
body.  A  lactometer  will  therefore  sink 
deeper  into  milk  of  a  low  specific  grav- 
ity than  into  milk  of  a  high  specific 
gravity. 

The  scale  of  the  Quevenne  lactometer 
is  marked  at  15  and  40,  and  divided  into 
25  equal  parts,  with  figures  at  each  five 
divisions  of  the  scale.  The  single  divis 
ions  are  called  degrees.  The  15  degree 
mark  is  placed  at  the  point  to  which  the 
lactometer  will  sink  when  lowered  into  a 
liquid  of  a  specific  gravity  of  1.015,  and 
the  40  degree  mark  at  the  point  to  which 
it  will  sink  when  placed  in  a  liquid  of  a 
specific  gravity  of  1.040. 

The  specific  gravity  is  changed  to  lacto- 
meter degrees  .  by  multiplying  by  1000 
and  subtracting   1000  from  the  product. 

Example:  Given,  the  specific  gravity  of  a 
sample  of  milk,  1.0345;  corresponding  lacto- 
meter degree,  1  0345x1000-1000=34.5. 

Conversely,  if  the  lactometer  degree 
is  known,  the  corresponding  specific 
gravity  is  found  by  dividing  by  1000 
and  adding  1  to  the  quotient  (34. 5 -=-1000  lactometer  floating 

in  milk  In  a  tin  cyl- 


FiG. 


Quevenne 


.0345;  .0345+1  =  1.0345). 


inder  (112). 


The  Lactometer  and  Its  Application.  95 

108.  Influence  of  temperature.  Like  most  liquids,  milk 
will  expand  on  being  warmed,  and  the  same  volume  will, 
therefore,  weigh  less  when  warm  than  before;  that  is, 
its  specific  gravity  will  be  decreased.  It  follows  then 
that  a  lactometer  is  only  correct  for  the  temperature  at 
which  it  is  standardized.  If  a  lactometer  sinks  to  the 
32-mark  in  a  sample  of  milk  of  a  temperature  of  60°  F., 
it  will  only  sink  to,  say  33,  if  the  temperature  of  the 
milk  is  50°  F.,  and  will  sink  farther  down,  e.  g.,  to  31, 
if  the  temperature  is  70°  F.  Lactometers  on  the  market 
at  present  are  generally  standardized  at  60°  F.  and  to 
show  the  correct  specific  gravity  the  milk  to  be  tested 
should  first  be  warmed  (or  cooled,  as  the  case  may  be) 
to  exactly  60°  F.  As  this  is  a  somewhat  slow  process, 
tables  have  been  constructed  for  correcting  the  results 
for  errors  due  to  differences  in  temperature  (see  Appen- 
dix, Table  V). 

109.  As  the  fat  content  of  a  sample  of  milk  has  a 
marked  influence  on  its  specific  gravity  at  different  tem- 
peratures, the  CO- efficient  of  expansion  of  fat  differing 
greatly  from  that  of  the  milk  serum,  the  table  cannot 
give  absolutely  accurate  corrections  for  all  kinds  of  milk, 
whether  rich  or  poor.  But  the  errors  introduced  by  the 
use  of  one  table  for  any  kind  of  whole  milk  within  a 
comparatively  small  range  of  temperature,  like  ten  de- 
grees above  or  below  60°,  are  too  small  to  have  any  im- 
portance outside  of  exact  scientific  work,  and  in  such, 
the  specific  gravity  is  always  determined  by  means  of  a 
picnometer  or  specific  gravity  bottle,  at  the  temperature 
at  which  this  has  been  calibrated.  In  taking  the  spe- 
cific gravity  of  a  sample  of  milk  by  means  of  a  lacto- 


96  Testing  Milk  and  Its  Products. 

meter,  the  milk  is  always  warmed  or  cooled  so  that  its 
temperature  does  not  vary  ten  degrees  either  way  from 
60°  F. 

1(0.  The  temperature  correction  table  for  whole  milk, 
given  in  the  Appendix  shows  that  if,  e.  g.,  the  specific 
gravity  of  a  sample  of  milk  taken  at  68°  F.  was  found  to 
be  1.034,  its  specific  gravity  would  be  1.0352  if  the  milk 
was  cooled  down  to  60°.  If  the  specific  gravity  given 
was  found  at  a  temperature  of  51°,  the  corrected  specific 
gravity  of  the  milk  would  be  1.0329. 

In  practical  work  in  factories  or  at  the  farm,  sufficiently 
accurate  temperature  corrections  may  generally  be  made 
by  adding  .1  to  the  lactometer  reading  for  each  degree 
above  60°  F.,  and  by  subtracting  .1  for  each  degree  be- 
low 60°;  e.  g.,  if  the  reading  at  64°  is  29. 5, it  will  be  about 
29.5+. 4  =  29.9  at  60°  F. :  and  34.0  at  52°  F.  will  be 
about  34.0 -.8=33.2  at  60°  F.  The  table  in  the  Appe7i- 
dix  gives  33.0  as  the  corrected  figure  in  both  cases. 

The  scale  of  the  thermometer  in  the  lactometer  should 
be  placed  above  the  lactometer  scale  so  that  the  tempera- 
ture may  be  read  without  taking  the  lactometer  out  of 
the  milk;  this  will  give  more  correct  results,  will  facil- 
itate the  reading  and  save  time. 

III.  N.  Y.  Board  off  Health  lactometer.  In  the  East,  and 
among  city  milk  inspectors  generally,  the  so  called  New 
York  Board  of  Health  lactometer  is  often  used.  This 
does  not  give  the  specific  gravity  of  the  milk  directly,  as 
is  the  case  with  the  Quevenne  lactometer;  but  the  scale 
is  divided  into  120  equal  parts,  known  as  Board  of  Health 
degrees^  the  mark  100  being  placed  at  the  point  to  which 
the  lactometer  sinks  when  lowered  into  milk  of  a  specific 


Cream  Te.\ting.  97 

gravity  of  1.029  (at  60°  F. );  this  is  considered  the  lowest 
limit  for  the  specific  gravity  of  normal  cows'  milk.  The 
zero  mark  on  the  scale  shows  the  point  to  which  the  lac- 
tometer will  sink  in  water;  the  distance  between  these 
two  marks  is  divided  into  100  equal  parts,  and  the  scale 
is  continued  below  the  100  mark  to  120.  As  100°  on  the 
Board  of  Health  lactometer  corresponds  to  29°  on  the 
Quevenne  lactometer,  the  zero  mark  showing  in  either 
case  a  specific  gravity  of  1,  the  degrees  on  the  former 
lactometer  may  easily  be  changed  into  Quevenne  lacto- 
meter degrees  by  multiplying  by  .29.  To  further  aid  in 
this  transposition,  table  III  is  given  in  the  Appendix^ 
showing  the  readings  of  the  two  scales  between  60°  and 
120°  on  the  Board  of  Health  lactometer. 

112.  Reading  the  lactometer.  For  determining  the  spe- 
cific gravity  of  milk  in  factories  or  private  dairies,  tin 
cylinders,  IJ  inches  in  diameter  and  10  inches 
high,  with  a  base  about  four  inches  in  diame- 
ter, are  recommended  (see  fig.  39)5  another 
form  of  specific  gravity  cylinders,  in  use  in 
chemical  laboratories,  is  shown  in  lig.  40. 
The  cylinder  is  filled  with  milk  of  a  tempera- 
ture ranging  between  50°  and  70°  F.,  to 
within  an  inch  of  the  top,  and  the  lactometer 
is  slowly  lowered  therein  until  it  floats;  it  is 
left  in  the  milk  for  about  half  a  minute  before 
lactometer  and  thermometer  readings  are 
taken,  both  to  allow  the  escape  of  air  which 
fintrravfty  ^las  been  mixed  with  the  milk  in  pouring  it 
cylinder.  preparatory  to  the  specific  gravity  determina- 
tion, and  to  allow  the  thermometer  to  adjust  itself  to  the 


98  Testing  Milk  and  Its  Products. 

temperature  of  the  milk.  The  lactometer  should 
not  be  left  in  the  milk  more  than  a  minute  before 
the  reading  is  taken,  as  cream  will  very  soon  begin  to 
rise  on  the  milk,  and  the  reading,  if  taken  later,  will  be 
too  high,  as  the  bulb  of  the  lactometer  will  be  floating 
in  partially  skimmed  milk  (23).  In  reading  thejac- 
tometer  degree,  the  mark  on  the  scale  plainly  visible 
through  the  upper  portion  of  the  meniscus  of  the  milk 
should  be  noted.  Owing  to  surface  tension  the  milk  in 
immediate  contact^  with  the  lactometer  stem  will  rise 
above  the  level  of  the  surface  in  the  cylinder,  and  this 
must  be  taken  into  consideration  in  reading  the  degrees. 
There  is  no  need  of  reading  closer  than  one  half  of  a  lac- 
tometer degree  in  the  practical  work  of  a  factory  or  a 
dairy. 

113.  Time  of  taking  lactometer  readings.  The  specific 
gravity  of  milk  should  not  be  determined  until  an  hour 
or  two  after  the  milk  has  been  drawn  from  the  udder, 
as  too  low  results  are  otherwise  obtained  (RecJmageVs 
phenomenon).^  The  cause  of  this  phenomenon  is  not 
definitely  understood;  it  may  come  from  the  escape  of 
gases  in  the  milk,  or  from  changes  occurring  in  the  me- 
chanical condition  of  the  nitrogenous  components  of  the 
milk.  The  results  obtained  after  a  couple  of  hours  will 
as  a  rule  come  about  one  degree  higher  than  when  the 
milk  is  cooled  down  directly  after  milking  and  its  specific 
gravity  then  determined. 

114.  Influence  of  bi-chromate  on  lactometer  readings. 
When  potassium  bichromate  is  added  to  milk  samples 
to  preserve  them  from  souring  (188),  the  specific  gravity 

1  Milchzeituag  1883,  419;  Bulletin  No.  43,  Chem.  Div.,  U.  S.  Department 
of  Agriculture,  p.  191;  Analyst  1894,  p  76. 


The  Lactometer  and  Its  Application.  99 

of  the  milk  is  thereby  increased;  with  the  quantity  usu- 
ally added  (^  gram  to  a  pint  of  milk)  the  increase  amounts 
to  about  1  lactometer  degree,  and  this  correction  of  lacto- 
meter readings  should  be  made  with  milk  samples  pre- 
served in  this  manner.  To  avoid  this  error,  Dr.  Eichloff  ^ 
recommends  using  a  solution  of  bi-chromate  in  water 
(43  grams  to  1  liter),  the  specifc  gravity  of  which  is 
1.032,  or  similar  to  that  of  average  milk;  5  cc.  of  this  so- 
lution is  required  for  a  pint  of  milk.  No  correction  is 
necessary  for  the  dilution  with  this  small  amount  of  liquid 
preservative. 

115.  Cleaning  of  lactometer.  The  lactometer  should  be 
cleaned  directly  after  using,  by  rinsing  with  cold  water; 
it  is  then  wiped  dry  with  a  clean  cloth  and  placed  in  the 
case. 

Calculation  of  Milk  Solids. 

116.  A  number  of  chemists  have  prepared  formulas  for 
the  calculation  of  milk  solids  when  the  fat  content  and 
the  specific  gravity  (lactometer  reading)  of  the  milk  are 
known.  By  careful  work  with  milk  tester  and  lacto- 
meter it  is  possible  by  means  of  these  formulas  to  deter- 
mine the  composition  of  samples  of  milk  with  consider- 
able accuracy  outside  of,  as  well  as  in  chemical  laborator- 
ies. As  the  complete  formulas  given  by  various  chemists 
(Behrend  and  Morgen,  Clausnitzer  and  Mayer,  Fleisch- 
mannn,  Hehner  and  Richmond,  Richmond,  Babcock)"are 
very  involved,  and  require  rather  lengthy  calculations, 
tables  facilitating  the  figuring  have  been  prepared.  The 
formulas  in  use  at  the  present  time,  in  this  country  and 


1  Technik  der  Milchpriifung,  p,  98. 

2  Agricultural  Science,  vol.  Ill,  p.  139. 


100  Testing  Milk  and  Its  Products. 

abroad,  are  those  proposed  by  Fleischmann,  Hehnerand 
Richmond,  and  Babcock.  Babcock's  formula  is  the  one 
generally  taught  in  American  dairy  schools  and  is  there- 
fore given  here;  it  forms  the  foundation  of  table  VI  for 
solids  not  fat  in  the  Appendix. 

By  the  use  of  these  tables  the  per  cents  of  solids  not  fat 
may  be  found,  corresponding  to  lactometer  readings  from 
26  to  36,  and  to  fat  contents  from  0  to  6  per  cent.  The 
formula,  as  amended  in  1895/  is  as  follows,  S  being  the 
specific  gravity  and/  the  per  cent,  of  fat  in  the  milk. 

(1QA  a Of  \ 

100—1  0753  Sf~V^^^^~^'^  ^"^ 

The  derivation  of  this  formula  is  explained  in  the  re- 
port referred  to. 

117.  Short  formulas.  The  tables  made  up  from  this 
formula,  giving  the  percentages  of  solids  not  fat  corres- 
ponding to  certain  per  cents,  of  fat  and  lactometer  read- 
ings, are  given  in  the  Appendix.  A  careful  examination 
of  the  same  discloses  the  fact  that  the  per  cent,  of  solids 
not  fat  increases  uniformly  at  the  rate  of  .25  per  cent,  for 
each  lactometer  degree,  and  .02  per  cent,  for  each  per 
cent,  of  fat.     This  relation  is  expressed  by  the  following 

simple  formulas: 

Solids  not  fat^}  L+.2f 
Totalsolids^iL+1.2f, 
L  being  the  lactometer  reading  at  60°  F.  .(specific  gravity 
X  1000  —  1000),  and/the  per  cent,  of  fat  in  the  milk. 

Rule:  a,  To  find  the  per  cent,  of  solids  not  faJL  in  milk,  add 
two-tenths  of  the  per  cent,  of  fat  to  one-fourth  of  the  lactometer 
reading,  and 

b,  To  find  the  per  cent,  of  total  solids  in  milk,  add  one  and 
two-tenths  times  per  cent,  of  fat  to  one-fourth  of  the  lactometer 
reading. 

1  Wisconsin  experiment  station,  twelfth  report,  page  120. 


The  Lactometer  and  Its  Application.  101 

These  formulas  and  rules  are  easily  remembered  and 
can  be  quickly  applied  without  the  use  of  tables.  The 
results  obtained  by  using  them  do  not  differ  more  than 
.04  per  cent,  from  those  of  the  complete  formula  for 
milks  containing  up  to  6  per  cent,  of  fat,  and  may  be 
safely  relied  upon  in  practical  work. 

Adulteration  of  Milk. 

HS.  Methods  of  adulteration.  The  problem  of  deter- 
mining whether  or  not  a  sample  of  milk  is  adulterated 
becomes  an  important  one  in  the  work  of  milk  inspectors 
and  dairy-  and  food  chemists.  Managers  of  creameries 
and  cheese  factories  are  also  sometimes  interested  in  as- 
certaining possible  adulterations  in  case  of  some  patron's 
milk,  although  at  present,  since  the  general  introduction 
of  the  Babcock  test  in  factories  and  the  payment  for  the 
milk  on  the  basis  of  the  amount  of  butter  fat  delivered, 
the  temptation  to  water  or  skim  the  milk  has  been  large- 
ly removed.  In  the  city  milk  trade,  especially  in  our 
larger  cities,  watered  or  skimmed  milk  is  still  frequently 
met  with,  in  spite  of  the  vigilance  of  their  milk  inspect- 
ors or  ofi&cers  of  the  city  boards  of  health. 

When  the  origin  of  a  suspected  sample  of  milk  is 
known,  a  second  sample  should,  when  possible,  be  taken  on 
the  premises  by  or  in  the  presence  of  the  inspector,  and  the 
composition  of  the  two  samples  compared.  If  the  sus- 
pected sample  is  considerably  lower  in  fat  content  than 
th^  second,  so-called  control-sample,  and  has  a  normal 
per  cent,  of  solids  not  fat,  it  is  skimmed;  if  the  solids  not 
fat  are  below  normal,  it  is  watered ;  and  if  both  these 
percentages  are  abnormally  low,  the  sample  is  most 
likely  both  watered  and  skimmed  (123). 


102  Testing  Milk  and  Its  Products. 

119.  Latitude  of  variation.  In  order  to  determine 
whether  or  not  a  sample  of  milk  is  skimmed  or  watered, 
or  both  skimmed  and  watered,the  per  cents,  of  fat  and  of 
solids  not  fat  in  the  sample  must  be  ascertained,  and  if  a 
control -sample  can  be  secured,  these  determinations  for 
both  samples  compared.  The  proper  latitude  to  be  al- 
lowed for  the  natural  variation  in  the  composition  of 
milk  diifers  according  to  the  origin  of  the  milk;  in  case 
of  milk  from  single  cows,  the  variations  in  fat  ccmEeht 
from  day  to  day  may  exceed  one  per  cent., although  under 
ordinary  conditions  the  per  cent,  of  fat  in  most  cows'  milk 
will  not  vary  that  much.     The  content  of  solids  not  fat 


is  more  constant,  and  rarely  varies  one-half  of  one  per 
cent,  from  day  to  day  with  single  cows.  Cows  in  heat  or' 
sicFcows  may  give  milk  differing  considerably  in  com- 
position from  normal  milk.^ 

120.  Mixed  herd  milk  is  of  comparatively  uniform  com- 
position on  consecutive  days,  and  as  most  milk  offered 
for  sale  or  delivered  to  factories  is  of  this  kind,  the  task 
of  the  milk  inspector  is  made  considerably  easier  and 
more  certain  on  this  account.  Daily  variations  in  herd 
milk  beyond  one  per  cent,  of  fat  and  one-half  per  cent,  of 
solids  not  fat,  are  suspicious  and  may  be  taken  as  fairly 
conclusive  evidence  of  adulteration.  This  is  especially 
true  in  case  the  control-sample  shows  a  comparatively 
low  content  of  fat  or  solids  not  fat  (155). 

121.  Legal  standards.  Where  a  control -sample  cannot 
be  taken,  the  legal  standards  of  the  various  states  for  fat 
or  solids  in  milk  are  used  as  a  basis  for  calculating  the 


1  Blythe,  Foods,  their  Composition  and  Analysis,  London,  1903,  p.  250 
et  seq. 


The  Lactometer  and  Its  Application.  103 

extent  of  adulteration  of  a  sample  of  milk.  A  list  of 
legal  standards  for  milk  in  this  country  and  abroad  is 
given  in  the  Appendix.  These  standards  determine  the 
limits  below  which  the  milk  offered  for  sale  within  the 
respective  states  must  not  fall.  Legally  it  matters  not 
whether  a  sample  of  milk  offered  for  sale  has  been 
skimmed  or  watered  by  the  dealer  or  by  the  cow;  in  the 
latter  case,  the  cows  producing  the  milk  are  of  a  breed 
or  a  strain  that  has  been  bred  persistently  for  quantity 
of  milk,  without  regard  to  its  quality.  In  most  states 
the  legal  standard  for  the  fat  content  of  milk  is  3  per 
cent..,  and  for  solids  not  fat  9  per  cent.  There  are,  how- 
ever, cows  which  some  times  produce  milk  containing  only 
2.5  to  2.8  per  cent,  of  fat,  and  less  than  8.5  per  cent, 
solids  not  fat.  Such  milk  cannot  therefore  be  legally 
sold  in  most  states  in  the  Union,  and  the  farmer  offering* 
such  milk  for  sale,  even  if  he  does  not  know  the  compo- 
sition of  the  milk  produced  by  his  cow,  is  as  liable  to 
prosecution  as  if  he  had  directly  watered  the  milk.  By 
mixing  the  milk  of  several  cows,  the  chances  are  that  the 
mixed  milk  will  contain  more  fat  and  solids  not  fat  than 
called  for  by  the  legal  standard;  if  such  should  not  be 
the  case,  cows  producing  richer  milk  must  be  added  to 
the  herd  so  as  to  raise  the  quality  of  the  herd  milk  up  to 
the  legal  standard,  or  the  cows  giving  very  thin  milk 
must  be  disposed  of. 

122.  The  specific  gravity  of  the  milk  solids.  A  calcala- 
tion  of  the  specific  gravity  of  the  milk  solids  is  of  consid- 
erable assistance  in  interpreting  the  results  of  analyses 
of  suspected  milk  samples.  The  milk  solids  vary  but 
slightly  in  specific  gravity,  viz.,  between  1.25  and  1.34, 


104  Testing  Milk  and  Its  Products. 

the  richer  milks  having  solids  of  low  specific  gravities. 
The  specific  gravity  of  the  solids  of  milk  is  calculated  by 
means  of  Fleischmann's  formula 

t 


S: 


100  s- 100 


s 

S  being  the  sp.  gr.  of  the  milk  solids,  s  that  of  the  milk 
and  t  the  total  solids  of  the  milk. 

Example:  A  sample  of  milk  has  iiegn^und  Lo  contain  13.0 
per  cent,  of  solids,  sp.  gr.  1.032;  then  ^^^^^|^^=3. 101  ;  13.0 
-3.101=9.899;  ^i=1.31  =  thespecificgravity  of  the  mi:k  solids. 

The  specific  gravity  of  the  solids  does  not  change  if 
the  milk  is  watered,  while  it  is  increased  when  the  milk 
is  skimmed.  If  a  sample  of  milk  of  the  composition 
given  in  the  preceding  example  had  been  watered  so  as 
to  reduce  the  solids  to  11.7  per  cent,  and  the  specific 
gravity  to  1.0291  (as  would  be  the  case  when  10  per  cent, 
of  water  was  added),  we  would  again  have,  by  calcula- 
tion as  above,  S  =  1.31.  If,  on  the  other  hand,  the  milk 
was  skimmed  so  as  to  reduce  the  solids  to  11.7  per  cent., 
thereby  increasing  the  specific  gravity  of  the  milk  to, 
say  1.035,  we  would  have  by  substituting  these  values 
in  the  preceding  formula,  S  =  1.41,  showing  conclusively 
that  the  milk  had  been  skimmed. 

Addition  of  skim  milk  to  whole  milk  would  have  the 
same  effect  as  skimming,  as  regards  the  composition  of 
the  latter,  and  the  specific  gravity  of  its  solids. 

The  specific  gravity  of  pure  butter  fat  at  60°  F.  is  .93, 
and  of  the  fat  free  milk  solids  1.5847  (Fleischmann). 
The  solids  of  skim  milk  have  a  specific  gravity  of  1.56. 
Samples  of  whole  milk,  the  solids  of  which  have  a  spe- 


The  Lactometer  and  Its  Application.  105 

cific  gravity  above  1.34  are  suspicious,  and  a  specific 
gravity  over  1.40  is  conclusive  evidence  of  skimming. 

To  facilitate  the  calculation  of  the  specific  gravity  of 
milk  solids,  table  IV  is  given  in  the  Appendix,  showing 
at  a  glance  the  value  of  ^"^^"'^  for  specific  gravities  be- 
tween 1.019  and  1.0869.  An  example  will  readily  illus- 
trate the  use  of  the  table. 

Uxample:  A  sample  of  milk  has  a  specific  gravity  of  1.0343 
and  contains  12.25  per  cent,  solids.  In  table  IV,  we  find  in  the 
horizontal  line  begioDing  with  1.034  under  the  column  headed 
0.0003,  the  figure  3.316,  which  is  the  value  for  ^^^'~^^  when 
8=1.0343.  Introducing  this  value  and  that  of  the  total  solids 
in  the  formula,  the  calculation  is  12.25-3.316=8.934;  12.25^ 
^  8.934=1.37.     The   specific   gravity  of  the  solids  in  this  case 

therefore  is  1.37. 
V  123.  To  recapitulate.     Adulteration  of  milk  by  water- 

ing or  skimming  or  both  may  be  established  by  a  com- 
parison of  the  composition  of  the  suspected  sample  with 
that  of  a  control-sample,  or  if  none  such  can  be  obtained, 
with  the  legal  standards.  If  the  composition  of  the  two 
samples  varies  appreciably,  the  milk  has  been  adulterated, 
and  the  character  of  the  adulteration  is  shown  from  the 
following  statement: 

//'  the  analysis  of  the  suspected  sample 
shoios  the  milk  is 

sp.  gr.  of  milk ")  .  ■) 

fat  and  solids  not  fat J  ^^^  [    watered 

^^- sp.  gr.   of  solids normal    ) 

^.      sp.  gr.  of  milk  and  of  Solids | ,  .  ,         ) 

solids  not  fat j  ^^^^        [skimmed 

fat  and  solids low  ) 

sp.  gr.  of  milk normal     ^    watered 

sp.  gr.  of  solids, normal  or  high  y       and 

fat  and  solids  not  fat low  )  skimmed 


106  Testing  Milk  and  Its  Products. 

The  extent  of  the  adulteration  is  determined  as  given 
below. 

124.  Calculation  of  extent  of  adulteration.^  In  the  fol- 
lowing formulas,  per  cents,  found  in  the  control  samples, 
if  such  are  at  hand,  are  always  substituted  for  the  legal 
standards. 

a.  Skimming. — 1.  If  a  sample  of  milk  has  been  skim- 
med, the  following  formula  will  give  the  number  of 
pounds  of  fat  abstracted  from  100  lbs.  of  milk: 

Fat  abstracted  =  (x)=  legal  standard  for  fat  — f,  .  (I) 
f  being  the  per  cent,  of  fat  in  the  suspected  sample. 

2.  The  following  formula  will  give  the  per  cent,  of  fat 
abstracted,  calculated  on  the  total  quantity  of  fat  origi- 
nally found  in  the  milk: 

x  =  i00— ^-^^^ ....     (tl) 

legal  standard  for  fat 

b.  Watering. — 1.  If  a  sample  is  watered,  the  calcula- 
tions are  most  conveniently  based  on  the  percentage  of 
solids  not  fat  in  the  milk: 

Per  cent,  of  foreign  (extraneous)  water  in  adulterated 

milk  =  100-,       ,^     J^r  V,       ,rr  ■     ■     ■    ^"'^ 
legal  standard  tor  solids  not  tat 

S  being  the  per  cent,  of  solids  not  fat  in  the  suspected 
sample. 

Example:  A  sample  of  milk  contains  7.5  per  cent,  solids  not 
fat;  if  the  legal  standard  for  solids  not  fat  is  9  per  cent., 

7  5  X  100 
100—  — — Q =  16.7,  shows  the  per  cent,  of  extraneous  water 

in  the  milk. 

2.  Watering  of  milk  may  also  be  expressed  in  per  cent, 
of  water  added  to  the  original  milk^  by  formula  IV: 

1  Woll,  Handbook  for  Farmers  and  Dairymen,  New  York,  1903,  pp.  236-7. 


The  Lactometer  and  Its  Application.  107 

Per  cent,  water  added  to  original  milk 
_  ,         100  X  leg.  stand,  for  sol.  not  fat 

100  X  9 
In  the  example  given  above,  — ^^-- —  —  100  =  20  per 

i .  o 

cent,  of  water  was  added  to  the  original  milk. 

c.  Watering  arid  sJcimming. — If  a  sample  has  been  both 
watered  and  skimmed,  the  extent  of  watering  is  ascer- 
tained by  means  of  formula  (III)  or  (lY),  and  the  fat 
abstracted  found  according  to  the  following  formula: 

Per  cent,  fat  abstracted  = 

,    .     ,         .      .  n     ..  .     leg. stand. for  sol.  not  fat     ,      ,^^, 
(x)  =  leg. stand. for iat xf  .  (V) 

Example:  A  sample  of  milk  contains  2.4  per  cent,  of  fat  and 
8.1  per  cent,  solids  not  fat;  then 

Extraneous  water  in  milk  — 100 '- — - — =10  per  cent. 

Fat  abstracted =3-^ ^/'  =.33  per  cent. 

100  Itjs.  of  the  milk  contained  10  lt)s.  of  extraneous  waterand 
.33  tb.  of  fat  had  been  skimmed  from  it. 

For  methods  of  detection  of  other  adulterations  and  of 

preservatives  in  dairy  products,   see   Chapter   X,    281 

et  seq. 


>  . 


CHAPTEE  YII. 
TESTING   THE    ACIDITY  OP  MILK  AND  CREAM. 

125.  Cause  of  Acidity  in  Milk.  Even  directly  after  milk 
is  drawn  from  the  udder  it  will  be  found  to  have  an  acid 
reaction,  when  phenolphtalein  is  used  as  an  indicator.^ 
The  acidity  in  fresh  milk  is  not  due  to  the  presence  of 
free  organic  acid's  in  the  milk,  like  lactic  or  citric  acid, 
but  to  acid  phosphates,  and  possibly  also  in  part  to  free 
carbonic  acid  gas  in  the  milk  or  to  the  acid  reaction  of 
casein.  Even  in  case  of  so-called  sweet  milk,  nearly 
fresh  from  the  cow,  a  certain  amount  of  acidity,  viz., 
on  the  average  about  .07  per  cent.,  is  therefore  found. 
When  the  milk  is  received  at  the  factory  it  will  rarely 
test  less  than  .10  per  cent,  of  acid,  calculated  as  lactic 
acid;  some  patrons  bring  milk  day  after  day  that  does 
not  test  over  .15  per  cent,  of  acid;  that  of  others  tests 
from  .20  to  .25  per  cent.,  and  some  lots,  although  very 
rarely,  will  test  as  high  as  .3  of  one  per  cent,  of  acid. 
It  has  been  found  that  milk  will  not  usually  smell  or 
taste  sour  or  ^'turned,"  until  it  contains  .30  to  .35  per 
cent,  of  acid. 

126  The  acidity  in  excess  of  that  found  normally  in 
milk  as  drawn  from  the  udder,  is  due  to  other  causes 
than  those  described.  Bacteriological  examinations  of 
milk  from  different  sources  and  of  the  same  milk  at  dif- 
ferent times  have  shown  that  there  is  a  direct  relation 


1  Freshly  drawn  milk  shows  an  amphoteric  reaction  to  litmus,  i.  e.,  it 
colors  blue  litmus  paper  red,  and  red  litmus  paper  faintly  blue. 


Testing  the  Acidity  of  Milk  and  Cream.  109 

between  the  bacteria  found  in  normal  milk,  and  its  acid- 
ity; the  larger  the  number  of  bacteria  per  unit  of  milk, 
the  higher  the  acidity  of  the  milk.  The  increase  in  the 
acidity  of  milk  on  standing  is  caused  by  the  breaking- 
down  of  milk  sugar  into  lactic  acid  through  the  influence 
of  acid-forming  bacteria.  Since  the  bacteria  get  into  the 
milk  through  a  lack  of  cleanliness  during  the  milking,  or 
careless  handling  of  the  milk  after  the  milking,  or  both, 
it  follows  that  an  acidity  test  of  new  milk  will  giviB  a 
good  clue  to  the  care  bestowed  in  handling  the  milk. 
Such  tests  will  show  which  patrons  take  good  care  of 
their  milk  and  which  do  not  wash  their  cans  clean,  or 
their  hands  and  the  udders  of  the  cows  before  milking, 
and  have  dirty  ways  generally  in  milking  and  caring  for 
the  milk.  The  acidity  test  is  always  higher  in  summer 
than  in  winter,  and  is  generally  high  in  case  of  milk 
kept  for  more  than  a  day  (Monday  milk),  or  delivered 
after  a  warm,  sultry  day  or  night.  The  bacteria  have  a 
chance  to  multiply  enormously  in  such  milk,  even  if  it 
be  kept  cooled  down  to  40°-50°  F.,  and  as  a  result  con- 
siderable quantities  of  lactic  acid  have  been  formed. 
The  determination  of  the  acidity  of  fresh  milk  is  ex- 
plained in  detail  below  (143). 

127.  Method  of  testing  acidity.  Methods  of  measuring 
the  acidity  or  alkalinity  of  liquids  by  means  of  certain 
chemicals  giving  characteristic  color  reactions  in  the 
presence  of  acid  or  alkaline  solutions  (so-called  volumetric 
methods  of  analysis)  have  been  in  use  for  many  years  in 
chemical  laboratories.  They  were  applied  to  milk  as 
early  as  1872  by  Soxhlet,^  and  the  method  worked  out 
by  Soxhlet  and  Henkel  has  since  been  in  general  use  by 

1  Jour.  f.  prakt.  Chemie,  1872,  p.  6, 19. 


110  Testing  Milk  and  Its  Products. 

European  chemists.  They  measured  out  50  cc.  of  milk 
to  which  was  added  2  cc.  of  a  2  per  cent,  alcoholic  solu- 
tion of  phenolphtalein,  and  this  was  titrated  with  a  one- 
fourth  normal  soda  solution'  (see  below).  In  this  country, 
Dr.  A.  G.  Manns  in  1890  published  the  results  of  work 
done  in  the  line  of  testing  the  acidity  of  milk  and 
cream,'  and  the  method  of  procedure  and  apparatus  pro- 
posed by  him  has  become  known  under  the  name  of 
Manns''  test,  and  has  been  advertised  as  such  by  dealers 
in  dairy  supplies. 

128.  Manns'  test.  The  acid  in  milk  or  cream  is  meas- 
ured by  using  an  alkali  solution  of  certain  strength,  with 
an  indicator  which  shows  by  a  change  of  color  in  the 
milk  when  all  its  acid  has  been  neutralized.  Any  of  the 
alkalies,  soda,  patash,  ammonia,  lime  or  barium  can  be 
used  for  making  the  standard  solution,  but  it  requires 
the  skill  and  apparatus  of  a  chemist  to  prepare  it  of  the 
proper  strength.  A  one-tenth  normal  solution"^  of  caustic 
soda  is  the  alkali  solution  used  most  frequently  in 
determining  the  acidity  of  milk,  and  is  the  solution  lab- 
eled Neutralize)'  of  the  Manns'  test. 


1  Fleischraann,  Lehrb.  d.  Milch wirtschaft,  8rd  ed.,  p.  57. 

2  Illinois  experiment  station,  bulletin  No.  9. 

3  Normal  solutions,  as  a  general  rule,  are  prepared  so  that  one  liter 
shall  contain  the  hydrogen  equivalent  of  the  active  reagent  weighed  in 
grams  (Sutton).  Caustic  soda  (NaOH  )  is  made  up  of  an  atom  each  of 
sodium  (Na),  oxygen  (O),  and  hydrogen  (H);  its  molecular  weight  is 
therefore 

23  +  16  +  1  =  40 
Na  O  H 
A  normal  soda  solution  then  is  made  by  dissolving  40  grams  of  soda  in 
water,  making  up  the  volume  to  lOOO  cc;  a  one-tenth  normal  solution  will 
contain  one-tenth  of  this  amount  of  soda,  or  4  grams  dissolved  in  one  liter. 
One  cubic  centimeter  of  the  latter  solution  will  contain  .004  gram  of  soda, 
and  will  neutralize  .009  gram  of  lactic  acid.  The  formula  for  lactic  acid  is 
C3HBO3  (see  page  16),  and  its  molecular  weight  therefore  3x12+6x1+3x16 
=90.  A  one-tenth  normal  solution  of  lactic  acid  contains  9  grams  per  liter, 
and  .009  gram  per  cubic  centimeter. 


Testing  the  Acidity  of  Milk  and  Cream.  Ill 

The  indicator  used  is  a  solution  of  phenolphtalein,  a 
light  yellowish  powder;  its  compounds  with  alkalies  are 
red.  in  weak  alkaline  solutions  pink  colored,  while  its 
acid  compounds  are  colorless.  The  phenolphtalein  solu- 
tion used  is  prepared  by  dissolving  10  grams  in  300  cc. 
of  90  per  cent,  of  alcohol  (Mohr). 

129.  In  testing  the  acidity  of  either  milk  or  cream  it 
is  necessary  to  measure  out  with  exactness  the  quantity 
of  liquid  to  be  tested;  Manns  recommended  using  a  50  cc. 
pipette.  This  amount  of  milk  or  cream  is  measured  into 
a  clean  tin,  porcelain  or  glass  cup,  a  few  drops  of  the 
phenolphtalein  solution  are  added,  and  the  Neutralizcr 
(or  alkali  solution)  is  cautiously  dropped  in  from  a  bur- 
ette, the  point  at  which  the  solution  stands  before  any 
is  drawn  out  being  noted.  By  constant  stirring  during 
this  operation  it  will  be  noticed  that  the  pink  color  formed 
by  the  addition  of  even  a  drop  of  alkali  solution  will  at 
first  entirely  disappear,  but  as  more  and  more  of  the  acid 
in  the  sample  becomes  neutralized,  the  color  will  disap- 
pear more  slowly,  until  finally  a  point  is  reached  when 
the  pink  color  remains  permanent  for  a  time.  No  more 
alkali  should  be  added  after  the  first  appearance  of  a 
uniform  pink  color  in  the  sample.  This  color  will  fade 
and  gradually  disappear  again  on  standing,  owing  to  the 
effect  of  the  carbonic  acid  on  the  air,  to  which  phenol- 
phtalein is  very  sensitive.  The  amount  of  the  alkali  solu- 
tion used  for  the  test  is  then  obtained  from  the  reading 
on  the  scales  of  the  burette.  The  per  cent,  of  acid  in  the 
sample  is  calculated  by  multiplying  the  number  of  cc.  of 
alkali  solution  used,  by  .009  and  dividing  the  product 
by  the  number  of  cc.  of  the  sample  tested,  the  quotient 
being  multiplied  by  100. 


\  a,e  So-.   '  ^ 

112  Testing  Milk  md  Its  Products. 

^       .,.,       c/c.  alkali  x  .009     ,^^^ 

Percent.  acidity  = -— ,XlOO 

c.  c.  sample  tested 

If  50  cc.  of  cream  required  32  cc.  of  alkali  solution  to 

produce  a  permanent  pink  color,  the  per  cent,  of  acid  in 

32  X.009 

the  cream  would  be -^ x  100  — .  58  per  cent.    A  part 

ou 

of  this  calculation  may  be  saved  by  using  a  factor  for 
multiplying  the  number  of  cc.  of  alkali  added  in  each 
test.  This  factor  is  obtained  by  dividing  009  (the  num- 
ber of  grams  of  lactic  acid  neutralized  by  one  cc.  of  alkali 
solution)  by  the  number  of  cc.  of  sample  tested,  and  mul- 
tiplying the  quoticLt  by  100.  If  a  50  cc.  pipette  is  used 
for  measuring  the  sami)le  to  be  tested,  the  factor  will  be 
(.009-^50)  X 100  =  . 018;  if  a  ^5  cc.  pipette  is  used,  the 
factor  will  be  (.009-^25)  x  100  =  .036;  and  if  a  20  cc. 
pipette  is  used,  (.009^20)  x  100  =  . 045  will  be  the  factor 
to  be  applied  in  calculating  the  per  cent,  of  acidity,  the 
number  of  cc.  of  alkali  used  being  in  all  cases  multiplied 
by  the  particular  factor  corresponding  to  the  volume  of 
the  sample  tested. 

130.  If  a  Babcock  milk  test  x^ipette  is  taken  for  meas- 
uring the  milk  or  cream  to  be  tested  for  acidity,  the 
factor  will  be  (.009--17.6)  X  100  =  . 051.  This  isso  nearly 
.05  that  sufficiently  accurate  results  may  be  obtained  by 
simply  dividing  the  number  of  cc.  used  by  two;  the  re- 
sult will  be  the  tenths  per  cent,  of  acid  in  the  sample  tested, 
e.  g.,  if  17.6  cc.  of  cream  required  12  cc.  of  one- tenth  nor- 
mal alkali  to  give  the  pink  color,  then  the  per  cent,  of 
acid  is  12-^2  =  .6  per  cent.  If  one- fifth  normal  alkali  is 
used  for  testing,  the  per  cent,  of  acidity  is  shown  directly 
by  the  number  of  cc.  used  (Vivian). 


Testing  the  Acidity  of  Milk  and  Cream. 


113 


131.  Manns'  testing  outfit.  The  apparatus  (see  fig. 
41)  and  chemicals  needed  for  testing  the  acidity  of  milk 
or  cream  by  the  so-called  Manns'  test  in- 
clude one  gallon  one-tenth  normal  alkali 
solution;  four  ounces  of  an  alcoholic  solu- 
tion of  phenolphtalein,  one  50  cc.  glass 
burette  with  stop-cock,  one  burette  stand, 
and  a  pipette  for  measuring  the  sample. 
This  outfit  will  make  about  100  tests  and 
is  sold  for  $5.00.^ 

132.  The  Alkaline  tablet  test.  Solid 
alkaline  tablets  were  proposed  by  Far- 
rington  in  1894,  as  a  substitute  for  the 
liquid  used  in  the  Manns'  test.^  It  was 
found  possible  to  mix  a  solid  alkali  car- 
bonate and  coloring  matter,  and  com- 
press the  mixture  into  a  small  tablet, 
which  would  contain  an  exact  amount  of 
alkali.  The  advantage  of  the  tablets  lies 
in  the  fact  that  they  will  keep  far  better 
than  a  standard  alkali  solution,  and 

they  can  be  easily  and  safely  sent 

lijli|ijij[    by  mail;  they  also  require  less  ap- 
paratus   and    are     considerably 

Fig.  41.  Apparatus  used  in  i       t       n     t        i 

Manns'  test.  chcapcr  than  standard  alkali  solu- 

tions; 1000  of  these  tablets,   costing  $2.00,   will  make 
about  400  tests.'     Similar  alkaline  tablets  were  placed 


1  Devarda's  acidimeter  (Milchzeitung,  1896,  p.  785)  is  based  on  the  same 
principle  as  Manns'  test;  one-tenth  soda  solution  is  added  to  100  cc.  of  milk 
in  a  glass-stoppered  graduated  flask,  2  cc.  of  a  4  per  cent,  phenolphtalein 
solution  being  used  as  an  indicator.  The  graduations  on  the  neck  of  the 
flask  give  the  "  degrees  acidity"  directly. 

2  Illinois  experiment  station,  bulletin  No.  82,  April,  1894. 

3  The  tablets  are  sold  by  dealers;^in;_dairy;supplie8. 
8 


114 


Testing  Milk  and  Its  Products. 


on  the  market  ia  Europe  at  about  the  same  time,  viz., 
Stokes'  Acidity  Pellets  in  1893,  and  Eichler's  Sceurepillen 
(acid-pills)  in  1895/ 

Two  methods  of  using  the  tablets  have  been  proposed, 
one,  for  the  titration  (determination  of  acidity)  of  ripen- 
ing cream  in  the  manufacture  of  sour-cream  butter;  and 
the  other,  for  determining  the  approximate  acidity  of 
different  lots  of  apparently  sweet  milk  or  cream. 

133.  Determination  of  acidity  in  sour  cream.  The 
method  is  equally  applicable  forthedetermiuationof  the 
acidity  of  sour  cream,  sour  milk 
and  butter- milk,  but  is  most  fre- 
quently employed  in  testing  the 
acidity  of  ripening  cream,  to  ex- 
amine whether  or  not  the  ripening 


Fig.  42.    Apparatus  used  for  determining  the  acidity  of  cream  or  milk. 

process  has  reached  the  proper  stage  for  churning  the 
cream.     The  apparatus  used  (see  fig.  42)  is  as  follows: 

1  Babcock  17.6  cc.  pipette. 

1  white  cup. 

1  Milchzeitung,  1895,  pp.  513-16. 


Testing  the  Acidity  of  Mill-  and  Cream.  115 

J  00  cc.  graduated  cylinders;  it  is  well  to  provide  two 
or  three  of  these^  although  only  one  is  strictly  necessary. 

134.  Preparation  of  the  solution.  The  tablet  solution 
forruerly  used  was  prepared  by  dissolving  five  tablets  in 
50  cc.  of  water;  with  20  cc.  of  cream  each  cubic  centi- 
meter of  this  solution  represents  .017  per  cent,  of  acid 
(lactic  acid)  in  the  sample  tested.  The  amount  of  acid 
in  a  given  sample  is  then  obtained  by  multiplying  the 
number  of  cubic  centimeters  of  the  tablet  solution  used 
by  .017.  . 

135.  According  to  a  suggestion  made  by  Mr.  C.  L. 
Fitch/  the  strength  of  the  solution  was  changed  in 
such  a  manner  that  the  percentages  of  acidity  are  indi- 
cated directly  by  the  number  of  cubic  centimeter  of  tab- 
let solution  used  in  each  test.  The  solution  may  be 
made  up  in  two  ways,  viz.,  by  use  of  a  20  cc.  or  a  17.6 
cc.  pipette. 

a.  Use  of  20  cc.  pipette.  When  a  20  cc.  pipette  is  used 
for  measuring  the  sample  to  be  tested,  the  tablet  solution 
is  prepared  by  dissolving  one  tablet  for  every  17  cc.  of 
water;  for  five  tablets  85  cc.  of  water  are  therefore  taken. 
When  made  in  this  way,  each  cubic  centimeter  of  solu- 
tion represents  .01  per  cent,  of  acid  in  the  sample  tested, 
10  cc.  being  equal  to  .10  per  cent,  acid,  32  cc.  to  .32  per 
cent,  65  cc.  to  .65  per  cent.,  etc. 

b.  Ise  of  17.6  cc.  pipette.  The  17.6  cc.  Babcock  milk 
test  pipette  may  be  used  for  measuring  the  sample  for 
acidity  testing,  and  the  results  read  directly  from  the 
graduated  cylinder,  if  the  tablet  solution  is  prepared  by 
taking  one  tablet  for  every  19.5  cc.  of  water;  five  tablets 
are  therefore  dissolved  in  97  cc.  of  water. 

1  Hoard's  Dairyman,  Sept.  3,  1897. 


116  Testing  Milk  and  Its  Products. 

136.  As  cream  during  its  ripening  process  under  our 
conditions  generally  has  from  .5  to  .6per  cent,  of  acid  be- 
fore it  is  ready  to  be  churned,  a  50  cc.  cylinderful  of  tablet 
solution  of  this  strength  will  not  be  sufficient  to  make  a 
test  of  cream  containing  over  .5  per  cent,  of  acid,  al- 
though it  is  enough  for  testing  the  cream  up  to  this  point 
during  the  ripening  process.  The  acid- testing  outfit 
should  therefore  contain  a  100  cc.  graduated  cylinder  in- 
stead of  one  of  50  cc.  capacity,  so  that  cream  of  any 
amount  of  acidity  up  to  1  per  cerit.  can  be  tested.  A 
tablet  solution  of  the  strength  given  has  not  only  the 
advantage  over  the  solution  previously  recommended 
(5  tablets  to  50  cc.  of  water)^  of  showing  the  per  cent,  of 
acidity  directly,  without  tables  or  calculations,  but  being 
weaker,  the  unavoidable  errors  of  determination  are  de- 
( reased  by  its  use. 

Equally  accurate  results  may  be  obtained  by  using 
solutions  made  up  according  to  method  a  or  method  b,  ex- 
plained in  the  preceding  ( 135) .  The  latter  method  (17. 6 
cc.  cream,  5  tablets  per  97  cc.  of  water)  has,  however,  the 
advantage  in  point  of  economy  of  apparatus,  since  a 
17.6  cc.  pipette  is  found  in  creameries  and  dairies  with 
the  Babcock  test  outfit  and  is  therefore  most  likely 
already  available  for  use  in  testing  the  acidity  of  cream. 
This  method  is  therefore  considered  preferable  and 
referred  to  as 

137.  The  standard  solution.  The  preparation  of  this 
solution  is  as  follows.  Five  tablets  are  placed  in  the 
100  cc.  cylinder  which  is  filled  to  the  97  cc.  mark  with 


1  Illinois  experiment  station,  bulletin  No.  32;  Wisconsin   experiment 
station,  bulletin  No.  52. 


Testing  the  Acidity  of  Milk  and  Cream.  117 

clean  soft  water.  ^  The  cylinder  is  tightly  corked,  shaken 
and  laid  on  its  side,  as  the  tablets  will  dissolve  more 
quickly  when  the  cylinder  is  placed  in  this  position  than 
when  left  upright  with  the  tablets  at  the  bottom.  Several 
cylinders  containing  the  tablet  solution  may  be  prepared 
at  a  time;  as  soon  as  one  is  emptied,  tablets  and  water 
are  again  added,  and  the  cyliuder  is  corked  and  placed 
in  a  horizontal  position.  In  this  way  fresh  solutions 
ready  for  testing  are  always  at  hand.  The  cylinder  is 
kept  tightly  corked  while  the  tablets  are  dissolving,  so 
that  none  of  the  liquid  is  lost  by  the  shaking.  It  is  well 
to  put  the  tablets  in  the  cylinder  with  water  at  night; 
the  solution  will  then  be  ready  for  use  in  the  morning. 
Excepting  a  flocculent  residue  of  inert  matter,  ^'set- 
tlings," which  will  not  dissolve,  the  tablets  must  all  dis- 
appear in  the  solution  before  this  is  used.  The  strength 
of  the  tablet  solution  does  not  change  perceptibly  by 
standing,  at  least  for  one  week.  The  only  precaution  nec- 
essary is  to  avoid  evaporation  of  the  solution  by  keeping 
the  cylinders  tightly  corked.  The  solid  tablets  will  not 
change  if  kept  dry,  any  more  than  dry  salt  changes  by  age. 
138.  Accuracy  of  the  tablets.  The  tablets  have  been  re- 
peatedly tested  by  chemists  and  found  to  be  accurate 
and  very  uniform  in  composition.  Tests  made  with  the 
tablets  according  to  the  directions  here  given  can  be 
therefore  relied  on  as  correct.  The  alkali  solution  is  very 
sensitive,  however,  and  should  not  be  measured  in  a  cylin- 
der which  has  been  previously  used  for  measuring  sulfu- 
ric acid,  as  the  smallest  drop  or  film  of  acid  from  a  dish 

1  Condensed  steam  or  rain  water  should  be  used,  and  not  hard  or 
alkali  water,  since  the  impurities  in  these  affect  the  strength  of  the 
tablet  solution. 


118  Testing  Milk  and  Its  Products. 

or  from  the  operator's  fingers  will  change  the  standard 
strength  of  the  tablet  solution. 

139.  Making  the  test.  The  cream  to  be  tested  is  thor- 
oughly mixed,  and  17.6  cc.  are  measured  into  the  cup. 
The  pipette  is  rinsed  once  with  water,  and  the  rinsings 
added  to  the  cream  in  the  cup.  A  few  cc.  of  the  tablet 
solution  prepared  as  given  above  are  now  poured  from 
the  cylinder  into  the  cream  and  mixed  thoroughly  with 
it  by  giving  the  cup  a  gentle  rotary  motion.  The  tablet 
solution  is  added  in  small  quantities  until  a  permanent 
pink  color  appears  in  the  sample.  The  number  of  cc.  of 
tablet  solution  which  has  been  used  to  color  the  cream 
is  now  read  off  on  the  scale  of  the  cylinder. 

In  comparing  the  results  of  one  test  with  another,  the 
same  shade  of  color  should  always  be  adopted.  The 
most  delicate  point  is  the  first  change  from  pure  white  or 
light  yellow  to  a  uniform  pink  color  which  the  sample 
shows  when  the  acid  contained  therein  has  just  been  neu- 
tralized. This  shade  of  color  is  easily  recognized  with  a 
little  practice.  The  pink  color  is  not  permanent  unless 
a  large  excess  of  the  alkaline  solution  has  been  added,  on 
account  of  the  influence  of  the  carbonic  acid  of  the  air 
(129),  and  the  operator  should  not  therefore  be  led  to 
believe  by  the  reappearance  of  the  white  color  after  a 
time,  that  the  point  of  neutralization  was  not  already 
reached  when  the  first  uniform  shade  of  pink  was 
observed. 

140.  Acidity  of  cream.  17.6  cc.  of  sweet  cream  is  gen- 
arally  neutralized  by  15-20  cc.  of  this  tablet  solution, 
representing  from  .15  to  .20  per  cent,  of  acid.  A  mildly 
sour  cream  is  colored  by  35  cc.  tablet  solution,  and  a  sour 


Testing  the  Acidity  of  Milk  and  Cream.  119 

cream  ready  for  churning  by  about  50  to  60  cc.  tablet  solu- 
tion. As  the  cream  ripens,  its  acidity  increases.  The 
rate  of  ripening  depends  largely  on  the  temperature  at 
which  the  cream  is  kept.  Cream  containing  .5  to  .6  per 
cent,  of  acid  will  make  such  butter  as  our  American 
market  demands  at  the  present  time.  Cream  showing 
an  acid  test  of  .  55  per  cent,  may  not  be  too  sour,  but  .  65 
per  cent,  of  acid  is  very  near,  if  not  on  the  danger  line, 
since  such  cream  is  likely  to  make  strong  flavored,  almost 
rancid  butter.  Each  lot  of  cream  should  be  tested  as 
soon  as  it  is  ready  for  ripening,  and  the  result  of  the  test 
will  show  whether  the  cream  should  be  warmed  or  cooled 
in  order  to  have  it  ready  for  churning  at  the  time  desired. 
Later  tests  will  show  the  rate  at  which  the  ripening  is 
progressing,  and  the  time  when  the  cream  has  reached 
the  proper  acidity  for  churning. 

141.  The  influence  of  the  richness  of  cream  on  the  acid 
test  has  been  studied  by  Professor  Spillman,^  and  others.- 
Since  the  acidity  developes  in  the  cream  serum,  it  follows 
that  an  acidity  of,  say  .5  per  cent,  in  a  40  per  cent, 
cream  represents  a  larger  acidity  than  in  20  per  cent.  - 
cream,  e.  g.  In  the  former  case  we  have  .5  gram  of 
acid  in  60  grams  of  serum  (  =.83  per  cent,  of  the  serum) ; 
in  the  latter  case  .5  gram  acid  is  found  in  80  grams 
serum  (=.63  per  cent,  of  the  serum).  Therefore,  rich 
cream  need  not  be  ripened  to  as  high  a  degree  of  acidity 
as  thin  cream.  A  table  is  given  in  the  Iowa  bulletin 
referred  to,  showing  the  relation  between  the  richness 
and  the  acidity  of  cream. 


1  Washington  experiment  station,  bulletin  No.  32. 

2  Chicago  Dairy  Produce,  April  21,  1900,  p.  30;  Iowa  Expt.  Sta.,  Bull.  52. 


120 


Testing  Mdk  and  Its  Products. 


?— 


142.  Spillman's  cylinder.  The  graduated  cylinder  shown  in 
fig.  48  was  devised  by  Professor  Spillnian  for  use  in  testing  the 
acidity  of  milk  and  cream  with  Farriugton's  alkaline  tablets. 
The  following  directions  are  given  for  making 
tests  with  this  piece  of  apparatus:' 

"All  that  is  needed  in  addition  to  the  acid-test 
graduate  shown  in  the  accompanying  illustra- 
tion, is  a  common  prescription  bottle  of  six  or 
eight  ounce  capacity,  and  a  package  of  Farriug- 
ton's alkaline  tablets.  Fill  the  bottle  with  water 
and  add  one  tablet  for  each  ounce  of  water  in 
the  bottle.  Shake  the  bottle  frequently  to  aid 
in  dissolving  the  tablets. 

''Making  the  test.  In  making  the  test,  the 
acid-test  graduate  is  filled  to  the  zero  mark  with 
the  milk  or  cream  to  be  tested.  The  tablet  solu- 
tion is  then  added,  a  little  at  a  time,  and  the 


Fig.  43.    Spill-  graduate  shaken  after  each  addition,  in  order  to 
man's   cylinder,  thoroughly  mix  the  milk  and  the  tablet  solution. 

used     in     dctGr-  • 

mining  the  acid-  ^^  shaking  the  graduate,  give  it  a  rotary  motion 
itj'  of  cream  or  to  prevent  spilling  anj^  of  the  liquid.  Continue 
™i^^-  adding  the  tablet  solution  until  a  permanent 

pink  color  can  be  detected  in  the  milk.  The  level  of  the  liquid 
in  the  graduate,  measured  by  the  scale  on  the  graduate,  will 
then  be  the  per  cent,  of  the  acidity  of  the  milk.  It  is  best  to 
stand  the  graduate  on  a  piece  of  white  paper,  so  that  the  first 
pink  coloration  of  the  milk  may  be  easily  detected." 

143.  Rapid  estimation  of  the  acidity  of  apparently  sweet 
milk  or  cream,  a,  Milk.  The  alkaline  tablet  method  offers 
a  ready  means  of  estimating  the  acidity  of  milk  or  cream 
that  is  still  sweet  to  the  taste.  The  selection  of  the  best 
kinds  of  milk  is  especially  important  in  pasteurizing  milk 
or  cream.  Investigations  have  shown  that  milk  which 
gives  the  highest  acid  test  contains,  as  a  rule,  a  larger 


1  Washington  experiment  station,  bulletin  No.  24. 


Testivg  the  Acidity  of  Mill-  and  Cream,  121 

number  of  bacteria  and  spores  not  destroyed  by  pasteur- 
ization than  does  milk  giving  a  low  acid  test  (126)5  ^^^ 
acidity  test  may  therefore  be  used  to  advantage  for  the 
purpose  of  selecting  milk  best  adapted  for  pasteurization, 
as  well  as  such  as  is  to  be  retailed  or  used  in  the  manu- 
facture of  high-grade  butter  and  cheese. 


jiiiiiiimillllll!!!^ 

■go -■i=^-H\o  "Measure 

Fig.  44.  Apparatus  used  for  rapid  estimation  of  the  acidity  of  appar- 
ently sweet  milk  or  cream. 

In  distinguishing  milk  fit  for  pasteurization  purposes 
from  that  which  is  doubtful,  an  arbitrary  standard  of 
two-tenths  of  one  per  cent,  of  acid  may  be  taken  as  the 
upper  limit  for  milk  of  the  former  kind.  The  appara- 
tus used  in  making  this  test  is  shown  in  the  accom- 
panying illustration  (fig.  44),  and  consists  of  a  white 
teacup;  a  four  ,  six-,  or  eight- ounce  bottle,  and  a  No.  10 
brass  cartridge  shell,  or  a  similar  measure.  A  solution 
of  the  tablets  in  water  is  first  prepared,  one  tablet  being 


122  Testing  Milk  and  Us  Products. 

always  added  to  each  ounce  of  water:  four  tablets  iu  a 
four-ounce  bottle;  six,  in  a  six-ounce  bottle,  etc.,  the 
amount  of  tablet  solution  prepared  depending  on  the 
number  of  tests  to  be  made  at  a  time.  The  bottle  is  filled 
up  to  its  neck  with  clean,  soft  water,  and  the  solution 
prepared  in  the  manner  previously  given  (137). 

144.  Operating  the  test.  As  each  lot  of  milk  is  brought 
to  the  creamery  in  the  morning  and  poured  into  the 
weigh  can,  it  is  weighed  and  the  cartridge-shell  dipper 
filled  with  the  milk  is  emptied  into  the  white  cup.  The 
same  or  another  :N^o.  10  shell  is  now  filled  twice  with  the 
tablet  solution  and  emptied  into  the  milk  in  the  cup. 
Instead  of  dipping  twice  with  one  measure  or  a  No.  10 
shell,  a  tin  measure  can  be  made  holding  as  much  as  two 
'No.  10  shells,  or  the  tablet  solution  may  be  made  of 
double  strength,  that  is,  two  tablets  to  each  ounce  of 
water  and  the  same  sized  measure  for  both  the  milk  and 
the  tablet  solution  used.  The  liquids  are  then  mixed 
in  the  cup  by  giving  this  a  quick,  rotary  motion,  and 
the  color  of  the  mixture  noticed.  If  the  milk  remains 
white  it  contains  more  than  two-tenths  of  one  per  cent, 
of  acid  and  should  not  be  used  for  pasteurization.  If  it 
is  colored  after  having  been  thoroughly  mixed  with  two 
measures  of  tablet  solution,  it  contains  less  than  this 
amount  of  acid  and  may,  as  far  as  acidity  goes,  be 
safely  used  for  pasteurization  or  for  any  other  purpose 
which  requires  thoroughly  sweet  milk.  The  shade  of 
color  obtained  will  vary  with  different  lots  of  milk;  the 
sweetest  milk  will  be  most  highly  colored,  but  a  milk 
retaining  even  a  faint  pink  color  with  two  measures  of 
tablet  solution  or  one  measure  of  the  double  strength 


Testing  the  Acidity  of  Milk  and  Cream.  '  123 

solution  to  one  measure  of  milk  contains  less  than  .2  per 
cent,  of  acid. 

By  proceeding  in  the  manner  described,  the  man  re- 
ceiving and  inspecting  the  milk  aj  the  factory  weigh-can 
is  able  to  test  the  acidity  of  the  milk  delivered  nearly  as 
quickly  as  he  can  weigh  it;  and  according  to  the  results 
of  the  test  he  can  send  the  milk  to  the  general  delivery 
vat  or  to  the  pasteurization  vat,  as  the  weigh  can  may 
be  provided  with  two  conductor  spouts. 

145.  Size  of  measure  necessary.  It  is  not  necessary  to 
use  a  No.  10  shell  for  a  measure  in  working  the  preced- 
ing method;  one  of  any  convenient  size  that  can  be  filled 
accurately  and  quickly,  will  answer  the  purpose  equally 
well,  if  a  measure  of  the  same  size  is  used  for  both  the 
sample  and  the  tablet  solution.  Each  measureful  of  tab- 
let solution  made  up  as  directed,  will  in  this  case  repre- 
sent one-tenth  per  cent,  of  acid  in  the  sample  tested. 

146.  b,  Cream.  Cream  can  be  tested  in  the  way  already 
described  for  testing  the  acidity  of  fresh  milk,  by  adding 
to  one  measureful  of  cream  in  the  cup  as  many  measures 
of  tablet  solution  as  are  necessary  to  change  the  color  of 
the  cream  when  the  two  liquids  are  thoroughly  mixed. 
If  one  measure  of  tablet  solution  colors  one  measure  of 
cream,  this  contains  less  than  .1  per  cent,  acid;  if  five 
measures  of  tablet  solution  are  required,  the  cream  con- 
tains about  .5  per  cent,  acid,  etc.  By  proceeding  in  the 
manner  described,  the  operator  can  estimate  the  acidity 
to  within  .05  per  cent,  of  acid,  if  half  measures  of  tablet 
solution  are  added.  The  results  thus  obtained  are  suffi- 
ciently delicate  for  all  practical  purposes. 


124  Testing  Milk  and  Its  Products. 

147.  Detecting  boracic-acid  preservatives  in  milk.  The  applica- 
tion of  the  alkaline  tablet  test  for  detecting  boracic  acid  in  milk 
was  first  discussed  in  bulletin  No.  52  of  Wisconsin  experiment 
station.  The  acidity  of  the  milk  is  increased  by  the  addition 
of  boracic  acid,  but  neitlier  the  odor  nor  the  taste  of  the  milk  is 
affected  thereby.  By  adding  to  sweet  milk  the  amount  of  bor- 
acic acid  which  will  keep  it  sweet  for  36  hours,  its  acidity  may 
be  increased  to  .35  per  cent.,  in  a  sample  of  milk  which  previ- 
ously tested  perhaps  only  .15  per  cent.  acid. 

As  before  stated,  unadulterated  milk  will  usually  smell  or  taste 
sour  or  "turned,"  when  it  contains  .30-35  per  cent,  acid  (118); 
milk  testing  as  high  as  this  limit,  which  neither  smells  nor 
tastes  sour  in  any  way,  is  therefore  in  all  probability  adulter- 
ated with  some  preparation  containing  boracic  acid  or  a  similar 
compound. 

148.  ''Alkaline  tabs."  These  are  not  the  alkaline  tablets,  but  a 
substitute  which  was  put  on  the  market  by  a  New  York  firm. 
The  outfit  furnish'ed  consisted  of  four  packages  of  paper  discs 
made  of  filter  paper,  each  of  about  the  size  of  an  old-style  cop- 
per cent;  two  packages  of  square  paper;  one  glass  of  about  10  cc. 
capacity,  and  one  small  glass  bottle.  An  investigation  of 
these  "Tabs"  soon  disclosed  the  fact  that  they  were  entirely 
inaccurate,  and  that  no  dependence  could  therefore  be  put  on 
the  results  obtained  by  their  use. 


CHAPTER  YIII. 
TESTING  THE  PURITY  OP  MILK. 

149.  The  Wisconsin  curd  test.  Cheese  makers  are  often 
troubled  with  so-called  floating  or  gassy  curds  which 
produce  cheese  defective  in  flavor  and  texture.  These 
faults  are  usually  caused  by  some  particular  lot  of  milk 
containing  impurities  that  cannot  be  detected  by  ordi- 
nary means  of  inspection.  The  Wisconsin  curd  test  is 
used  to  detect  the  source  of  these  defects  and  thus  enable 
the  cheese  maker  to  exclude  the  milk  from  the  particular 
farm  or  cow  to  which  the  trouble  is  traced.  This  test  is 
similar  in  principle  to  tests  that  have  for  many  years 
past  been  in  use  in  cheese-making  districts  in  Europe, 
notably  in  Switzerland/  but  was  worked  out  independ- 
ently at  the  Wisconsin  Dairy  School  in  1895  and  has 
become  generally  known  as  the  "Wisconsin  Curd  Test" 
from  the  description  of  it  in  the  report  of  the  Wisconsin 
experiment  station  for  1895.' 

The  apparatus  used  for  the  test  was  greatly  improved 
in  1898,  and  a  description  of  the  improved  test  is  given 
in  bulletin  No.  67  and  the  annual  report  of  this  Station 
for  1898,^  from  which  source  the  accompanying  illustra- 
tions are  taken  (see  figs.  44  and  45). 

150.  Method  of  making  the  test.  Pint  glass  jars,  thor- 
oughly cleaned  and  sterilized  with  live  steam,  are  pro- 

1  Herz,  Unters.  d.  Kuhmilch,  Berlin,  1889,  p.  87  ;  Siats,  Unters.  landw, 
Wicht.  Stoffe,  1897,  pp.  129-131. 

2  Twelfth  report,  p.  148. 

3  Fifteenth  report,  pp.  47-53. 


126 


Testing  Milk  and  Its  Products. 


vided;  they  are  plainly  numbered  or  tagged,  one  jar 
being  provided  for  each  lot  of  milk  to  be  tested.  The 
jars  are  filled  about  two-thirds  full  with  milk  from  the 
various  sources;  it  is  not  necessary  to  take  any  exact 
quantity;  they  are  then  placed  in  a  water  tank,  the  water 


Fig.  44.  The  Wigconsin  curd  test.  l,Test  jars  draining:  2,  whey  outlet; 
3,  te.st  jars  in  water  tank;  4,  test  jars  in  parts;  5,  stop  cock  for  water;  6, 
stand  to  support  cover. 


Fig.  45.  Cross-section  of  the  Wlsconsin'curd  test.  T  J-TJ",  testing  jars 
Showing  different  stagesof  test;  WL,  water  line;  M,  milk;  F,  frame;  WS, 
stand  to  support  cover;  AI  drain  holes;  WO,  water  outlet;  DP,  drain  pail. 


Testing  the  Parity  of  MWk.  127 

of  which  is  heated  until  the  milk  in  the  jars  has  a  tem- 
perature of  98°  F.  The  thermometer  used  must  not  be 
transferred  from  one  sample  to  another,  unless  special 
precautions  are  taken,  for  fear  of  contaminating  the  pure 
lots  of  milk  by  impure  ones. 

When  the  milk  has  reached  a  temperature  of  98°,  add 
to  each  sample  ten  drops  of  rennet  extract,  and  mix  by 
giving  the  jar  a  rolary  motion.  The  milk  is  thus  cur- 
dled, and  the  curd  allowed  to  stand  for  about  twenty 
minutes  until  it  is  firm.  It  is  then  cut  fine  with  a  case 
knife,  and  after  settling,  the  whey  is  poured  off.  The 
best  tests  are  made  when  the  separation  of  the  whey  is 
most  complete.  By  allowing  the  samples  to  stand  for  a 
short  time,  more  whey  can  be  poured  off,  and  the  cui  d 
thereby  rendered  firmer.  The  water  around  the  jars  is 
kept  at  a  temperature  of  98°,  the  vat  is  covered,  and  the 
curds  allowed  to  ferment  in  the  sample  jars  for  six  to 
twelve  hours. 

During  this  time  the  impurities  in  any  particular  sam- 
ple will  cause  gases  to  be  developed  in  the  curds  so  that 
by  examining  these,  by  smelling  of  them  and  cutting 
them  with  a  sharp  knife,  those  having  a  bad  flavor,  or  a 
spongy  or  in  any  way  abnormal  texture  may  be  easily 
detected,  and  the  milk  from  which  it  was  made,  thereby 
determined. 

151.  By  proceeding  in  the  same  way  with  the  milk 
from  the  difi'erent  cows  in  a  herd,  the  mixed  milk  of 
which  produced]abnormal  curds,  the  source  of  contami- 
nation in  the  herd  may  be  located.  Very  often  the 
trouble  will  be  found  to  come  from   the   cows'  drinking 


128  Testing  Milk  and  Its  Products. 

foul  stagnant  water  or  from  fermenting  matter  in  the 
stable.  In  the  former  case  the  pond  or  marsh  must  be 
fenced  off,  or  the  cows  kept  away  from  it  in  other  ways; 
in  the  latter,  a  thorough  cleaning  and  disinfection  of  the 
premises  are  required.  If  the  milk  of  a  single  cow  is 
the  source  of  contamination,  it  must  be  kept  by  itself, 
until  the  milk  is  again  normal;  under  such  conditions 
the  milk  from  the  healthy  cows  may,  of  course,  safely  be 
sent  to  the  factory. 

152.  The  fermentation  test.  The  Gerber  fermentation  test  (see 
fig.  -46)  furnishes  a  convenient  method  for  examining  the  purily 
of  different  lots  of  milk.  The  test  consists  of  a  tin  tank  which 
can  be  heated  by  means  of  a  small  lamp,  and  into  which  a  rack 
fits,  holding  a  certain 
number  of  cylindrical 
glass  tubes;  these  are  all 
numbered  and  provided 
with  a  mark  and  a  tin 
cover.  In  making  the 
test,  the  tubes  are  filled 
to  the  mark  with  milk, 
the  number  of  each  tube 
being  recorded  in  a  note 
book,  opposite  the  name 
of  the  particular  patron  whose  milk  was  placed  therein.  The 
tubes  in  the  rack  are  put  in  the  tank,  which  is  two-thirds  full 
of  water;  the  temperature  of  the  water  is  kept  at  104-10()°  F.  for 
six  hours,  when  the  rack  is  taken  out,  the  tubes  gently  shaken, 
and  the  appearance  of  the  milk,  its  odor,  taste,  etc,  carefully 
noted  in  each  case. 

The  tubes  are  then  again  heated  in  the  tank  at  the  same 
temperature  as  before,  for  another  six  hours,  when  observations 
of  the  appearance  of  the  milk  in  each  tube  are  once  more  taken. 


Fig.  46.  The  Gerber  fermentation  test. 


1  Die  praktiscbe  Milcbpriifung,  p.  8.5. 


Testing  the  Purity  of  Milk. 


129 


The  tainted  milk  may  then  easily  be  discovered  by  the  abnor- 
mal coagulation  of  the  sample.  According  to  Gerber,^  good  and 
properly  handled  milk  should  not  coagulate  in  less  than  twelve 
hours,  when  kept  under  the  conditions  described,  nor  show 
anything  abnormal  when  coagulated.  Milk  from  sick  cows 
and  from  cows  in  heat,  or  with  diseased  udders,  will  always 
coagulate  in  less  than  twelve  hours.  If  the  milk  does  not 
curdle  within  a  day  or  two,  it  should  be  tested  for  preserva- 
tives (290). 

153.  The  Monrad  rennet  test  is  used  by  cheese  makers 
for  determining  the  ripeness  of  milk.     Fig.  47  shows  the 

apparatus  used  in  the  test. 
5  cc.  of  rennet  extract  is 
measured  by  means  of  a  pip- 
ette into  a  50  cc.  flask;  the 
pipette  is  rinsed  with  water 
and  the  flask  filled  to  the  mark 
with  water.  160  cc.  of  milk 
is  now  measured  into  the  tin 
basin  from  the  cylinder  and 
slowly  heated  to  exactly  86° 
F.  5  cc.  of  the  diluted  rennet 
solution  is  then  quickly  added 
to  the  warm  milk  and  the 
time  required  for  coagulation 
noted.  ^  Milk  sufficiently  ripe 
for  Cheddar  cheese  making 
will  coagulate  in  30-60  sec- 
onds, according  to  the  strength  of  the  rennet  extract 
used. 


Fig.  47.  The  Monrad  rennet  test. 


1  Die  praktische  Milchpriifung,  p.  85. 
•2  Decker,  Cheese  Making,  1900,  p,  36. 


130 


Testing  Milk  and  Its  Products. 


154.  The  Marschall  rennet  test  is  used  for  the  same 
purpose  as  the  Monrad  test.  The  time  required  for 
coagulatiug  the  milk  is  shown  directly  by  a  scale  given 

on   the    apparatus  (fig. 

48). 

The  directions  for  this 
test  are  as  follows:  Fill 
the  small  glass  with  pure 
water  up  to  the  mark, 
pour  into  it  one  cc.  of  ren- 
net extract  and  rinse  the 
pipette  in  the  same 
water.  Fill  the  tin  cup 
with  milk  to  the  zero  mark,  add  the  rennet,  mix  thor- 
oughly and  allow  it  to  stand.  The  ripeness  of  different 
samples  of  milk  is  shown  by  the  amount  that  flows  out 
before  the  milk^coagulates. 


Fig.  48.    The  Marschall  rennet  test. 


OHAPTEE  IX. 
TESTING  MILK  ON  THE  PARH. 

155.  Variations  in  milk  of  single  cows.  The  variations 
in  the  tests  of  milk  of  single  cows  from  milking  to  milk- 
ing or  from  day  to  day,  are  greater  than  many  cow- 
owners  suspect.  There  seems  to  be  no  uniformity  in  this 
variation,  except  that  the  quality  of  the  milk  produced 
generally  improves  with  the  progress  of  the  period  of 
lactation;  even  this  may  not  be  noticeable,  however, 
except  when  the  averages  of  a  number  of  tests  made  at 
different  stages  during  the  lactation  period  are  compared 
with  each  other.  When  a  cow  gives  her  maximum 
quantity  of  milk,  shortly  after  calving,  the  quality  of 
her  milk  is  generally  poorer  (by  one  per  cent,  of  fat  or 
less)  than  when  she  is  drying  off.  Strippers'  milk  is 
therefore  as  a  rule  richer  in  fat  than  the  milk  of  fresh 
cows. 

156.  By  testing  separately  every  milking  of  a  number 
of  cows  through  their  whole  period  of  lactation,  the 
results  obtained  have  seemed  to  warrant  the  following 
conclusions  in  regard  to  the  variations  in  the  test  of  the 
milk  from  single  cows,  and  it  is  believed  that  these  con- 
clusions allow  of  generalization.^ 

1.  Some  cows  yield  milk  that  tests  about  the  same  at 


1  Illinois  experiment  station,  bulletin  No.  24. 


132  Testing  Milk  and  Its  Products. 

every  milking,  and  generally  give  a  uniform  quantity  of 
milk  from  day  to  day. 

2.  Other  cows  give  milk  that  varies  in  an  unexplain 
able  way  from  one  milking  to  another.  Neither  the 
morning  nor  the  evening  milking  is  always  the  richer, 
and  even  if  the  interval  between  the  two  milkings  is 
exactly  the  same,  the  quality  as  well  as  the  quantity  of 
milk  produced  will  vary  considerably.  Such  cows  are 
mostly  of  a  nervous,  excitable  temperament,  and  are 
easily  affected  by  changes  in  feed,  drink,  or  surrounding 
conditions. 

3.  The  milk  of  a  sick  cow,  or  of  a  cow  in  heat,  as  a 
rule,  tests  higher  than  when  the  cow  is  in  a  normal  con- 
dition; the  milk  yield  generally  decreases  under  such 
conditions;  marked  exceptions  to  this  rule  have,  how- 
ever, been  observed. 

4.  Half-starved  or  underfed  cows  may  give  a  small 
yield  of  milk  testing  higher  than  when  the  cows  are 
properly  nourished,  probably  on  account  of  an  accompa- 
nying feverish  condition  of  the  animal.  The  milk  is, 
however,  more  generally  of  an  abnormally  low  fat  con- 
tent, which  may  be  readily  increased  to  the  normal  per 
cent,  of  fat  by  liberal  feeding. 

5.  Fat  is  the  most  variable  constituent  of  milk,  while 
the  solids  not  fat  vary  within  comparatively  narrow 
limits.  The  summary  of  the  analyses  of  more  than  2400 
American  samples  of  milk  calculated  by  Cooke^  shows 
that  while  the  fat  content  varies  from  3.07  to  6.00  per 
cent.,  that  of  casein  and  albumen  varies  only  from  2.92 
to  4.30  per  cent.,  or  less  than  one  and  one-half  per  cent., 

1  Vermont  experiment  station,  report  for  1890,  p.  97. 


Testing  Milk  on  the  Farm.  133 

and  the  milk  sugar  and  ash  content  increases  but  little 
(about  .69  per  cent.)  within  the  range  given. 

6.  A  test  of  only  one  milking  may  give  a  very  erro- 
neous impression  of  the  average  quality  of  a  certain 
cow's  milk.  A  composite  sample  (see  175)  taken  from 
four  or  more  successive  milkings  will  represent  the 
average  quality  of  the  milk  which  a  cow  produces  at 
the  time  of  sampling. 

157.  The  variations  that  may  occur  in  testing  the  milk 
of  single  cows,  are  illustrated  by  the  following  figures 
obtained  in  an  experiment  made  at  the  Illinois  experi- 
ment station,  ^  in  which  the  milk  of  each  of  six  cows  was 
weighed  and  analyzed  daily  during  the  whole  period  of 
lactation.  Among  the  cows  were  pure- bred  Jerseys, 
Shorthorns  and  Holsteins,  the  cows  being  from  three  to 
eight  years  of  age  and  varying  in  weight  from  850  to 
1350  lbs.  During  a  period  of  two  months  of  the  year, 
the  cows  were  fed  a  heavy  grain  ration  consisting  of  12 
lbs.  of  corn  and  cob  meal,  six  lbs.  of  wheat  bran,  and  six 
lbs.  of  linseed  meal,  per  day  per  head.  This  system  of 
feeding  was  tried  for  the  purpose  of  increasing,  if  possi- 
ble, the  richness  of  the  milk.  The  influence  of  this  heavy 
grain  feed,  as  well  as  that  of  the  first  pasture  grass  feed, 
on  the  quality  and  the  quantity  of  the  milk  produced  is 
shown  in  the  following  table,  which  gives  the  complete 
average  data  for  one  of  the  cows  (No.  3).  The  records 
of  the  other  cows  are  given  in  the  publication  referred 
to;  they  were  similar  to  the  one  here  given  in  so  far  as 
variations  in  quality  are  concerned. 


Bulletin  No.  24, 


134 


Testing  Milk  and  Its  Products. 


Average  results  obtained  in  weighing  and  testing  a  cove's  milk 
daily  during  one  period  of  lactation. 


MONTH. 


December 
January .. 
February. 

March 

April 

May 

June 

July 

August 


^^ 


920 
927 
103.5 
1047 
1054 
1079 
1105 
1180 
1130 


Daily  Milk 
yield. 


Sifi 


12.1 
16.0 
16.1 
14.3 
13.8 
14  5 
12.1 
9.3 
6.4 


16.0 
17.7 
177 
16.0 
16  5 
17.2 
14.0 
122 


o 


10.0 
14.0 
13  5 
12.5 
11.5 
10.0 
9.2 
6.0 
3.5 


Test  of  one  day 'j 
milk. 


38 
3.7 
3.6 
38 
40 
3.8 
3.9 
4.2 
4.7 


4.9 
4.6 
5.8 
4.7 
5.8 
4.6 
4.6 
6.2 
7.9 


1^ 


3.0 

2.7 
3.2 
3.4 
30 
3.4 
3.2 
2.8 
2.9 


Yield  of  fat  per 
day. 


.34 

.44 

.51 

.50 

.46 

.44 

.35, 

.271 

.16] 


158.  The  average  test  of  this  cow' s  milk  for  her  whole 
period  of  lactation  was  3.8  per  cent,  of  fat  (i.  e.,  the  total 
quantity  of  fat  produced  -^  total  milk  yield  X  100);  twice 
during  this  time  the  milk  of  the  cow  tested  as  high 
as  5.8  per  cent,  and  once  as  low  as  2.7  percent.  The 
average  weight  of  milk  produced  per  day  by  the  cow 
was  14  lbs. ;  this  multiplied  by  her  average  test,  3. 8, 
shows  that  she  produced  on  the  average  .  53  fbs. ,  or  about 
one-half  of  a  pound,  of  butter  fat  per  day  during  her  lac- 
tation period.  If,  however,  her  butter-producing  capac- 
ity had  been  judged  by  the  test  of  her  milk  for  one  day 
only,  this  test  might  have  been  made  either  on  the  day 
when  her  milk  tested  5.8  per  cent.,  or  when  it  was  as  low 
as  2. 7  per  cent.  Both  of  these  tests  were  made  in  mid- 
winter when  the  cow  gave  about  16  lbs.  of  milk  a  day. 
Multiplying  this  quantity  by  .058  gives  .93  lbs.  of  fat,  and 
by  .027  gives  .43  lbs.  of  fat.      Either  result  might  show 


Testing  MUlc  on  the  Farm.  135 

the  butter  fat  produced  by  the  cow  on  certain  days,  but 
neither  gives  a  correct  record  of  her  actual  average  daily 
performance  for  this  lactation  period. 

A  sufficient  number  and  variety  of  tests  of  the  milk  of 
many  cows  have  been  made  to  prove  that  there  is  no 
definite  regularity  in  the  daily  variations  in  the  richness 
of  the  milk  of  single  cows.  The  only  change  in  the  qual- 
ity of  milk  common  to  all  cows  is,  as  stated,  the  natural 
increase  in  fat  content  as  the  cows  are  drying  off,  and 
even  in  this  case  the  improvement  in  the  quality  of  the 
milk  sometimes  does  not  occur  until  the  milk  yield  has 
dwindled  down  very  materially. 

159.  Causes  of  variations  in  fat  content.  The  quality  of 
a  cow's  milk  is  as  a  rule  decidedly  influenced  by  the  fol- 
lowing conditions: 

Length  of  interval  between  milkings. 

Change  of  feed. 

Change  of  milkers. 

Eapidity  of  milking. 

Eough  treatment. 

Exposure  to  rain  or  bad  weather. 

Unusual  excitement  or  sickness. 

160.  Disturbances  like  those  enumerated  frequently 
increase  the  richness  of  the  milk  for  one,  and  sometimes 
for  several  milkings,  but  a  decrease  in  quality  follows 
during  the  reaction  or  the  gradual  return  to  normal  con- 
ditions, and  taken  as  a  whole  there  is  a  considerable 
falling  off  in  the  total  production  of  milk  and  butter  fat 
by  the  cow,  on  account  of  the  nervous  excitement  which 
she  has  gone  through.  Aside  from  changes  due  to  well- 
definable  causes  like  those  given  above,  the  quality  of 


136  Testing  Milk  and  Its  Products. 

some  cows'  milk  will  often  change  very  considerably 
without  any  apparent  cause.  The  dairyman  who  is  in 
the  habit  of  making  tests  of  the  milk  of  his  individual 
cowS  at  regular  intervals  will  have  abundant  material 
for  study  in  the  results  obtained,  and  he  will  soon  be 
able  to  tell  from  the  tests  made,  if  these  are  continued 
for  several  days,  whether  or  not  the  cows  are  in  a  normal 
healthy  condition  or  have  been  subjected  to  excitement 
or  abuse  in  any  way. 

161.  Number  of  tests  required  during  a  period  of  lacta- 
tion in  testing  cows.  The  daily  records  of  the  six  cows 
referred  to  on  page  133  give  data  for  comparing  their 
total  production  of  milk  and  butter  fat  during  one  period 
of  lactation,  as  found  from  the  daily  weights  and  tests 
of  their  milk,  with  the  total  amount  calculated  from 
weights  and  tests  made  at  intervals  of  7,  10,  15  or  30 
days.  The  averages  of  all  results  obtained  with  each  of 
the  six  cows  show  that  weighing  and  testing  the  milk  of 
a  cow  every  seventh  day  gave  98  per  cent,  of  the  total 
milk  and  butter  fat,  which  according  to  her  daily  record 
was  the  total  product.  Tests  made  once  in  two  weeks 
gave  97.6  per  cent,  of  the  total  milk,  and  98.5  per  cent, 
of  the  total  butter  fat,  and  tests  made  once  a  month,  or 
only  ten  times  during  the  period  of  lactation,  gave  96.4 
per  cent,  of  the  total  milk,  and  97  per  cent,  of  the  total 
production  of  butter  fat. 

162.  The  record  of  one  of  the  cows  will  show  how 
these  calculations  are  made:  It  was  found  from  the 
daily  weights  and  tests  that  cow  No.  1,  in  one  lactation 
period  of  307  days,  gave  5,044  ItDs.  of  milk  which  con- 
tained 254  lbs.  of  butter  fat.      Selecting  every  thirtieth 


Testing  Milk  on  the  Farm. 


137 


day  of  her  record  as  testing  day,  the  total  production  of 
milk  and  fat  is  shown  to  be  as  follows: 

Production  of  milk  and  butter  fat  per  day. 


Testing  day. 

Weight  of  milk. 

Test  of  milk. 

Yield  of  butter  fat. 

Nov.    4 

R)S. 
20.5 
18.7 
17.7 
20.0 
18.2 
19.5 
17.7 
13.1 
12.2 
3.2 

per  cent. 
4.7 
4.6 
4.9 
4.5 
4.7 
4.4 
4.8 
5.5 
6.2 
7.2 

lbs. 
.96 

Dec.     4 

.86 

Jan.     3 

Feb.     2 

Mar.    3 

.86 
.90 

.86 

April  2 

May    2 

June    1  

.81 

.85 

.72 

July    1 

July  31 

.76 
.23 

Total 

160.8  lbs. 
16.08  lbs. 

7.81  lbs. 

Average  per  day. 

4.85 

.78  lbs. 

The  average  daily  production  of  the  cow,  according  to 
the  figures  given  in  the  preceding  table,  was  about 
16  lbs.  of  milk,  containing  .78  lbs.  of  butter  fat.  Multi- 
plying these  figures  by  307,  the  number  of  days  during 
which  the  cow  was  milked,  gives  4,912  lbs.  of  milk  and 
240  lbs.  of  fat.  This  is  132  lbs.  of  milk  and  14  lbs.  of  fat 
less  than  the  total  weights  of  milk  and  butter  fat,  as 
found  by  the  dally  weights  and  tests,  or  2.8  and  5.5  per 
cent,  less,  for  milk-  and  fat  production,  respectively. 
This  is,  however,  calculated  from  only  ten  single  weights 
and  tests,  while  it  required  over  600  weighings  and  300 
tests  of  the  milk  to  obtain  the  exact  amount. 

Similar  calculations  from  the  records  of  the  other  cows 
gave  fully  as  close  results,  showing  that  quite  satisfac- 
tory data  as  to  the  total  production  of  milk  and  butter 


138 


Testing  Milk  and  Its  Products. 


of  a  cow  may  be  obtained  by  making  correct  weighings 
and  tests  of  her  full  day's  milk  once  every  thirty  days. 

163.  When  to  test  a  cow.'  The  Vermont  experiment 
station  for  several  years  made  a  special  study  of  the  ques- 
tion when  a  cow  should  be  tested  in  order  to  give  a  correct 
idea  of  the  whole  year' s  performance,  when  only  one  or  two 
tests  are  to  be  made  during  the  lactation  period.  ~  The  re- 
sults obtained  may  be  briefly  summarized  as  follows: 

a.  As  to  quality  of  milk  produced.  If  two  tests  of  each 
cow's  milk  are  to  be  made  during  the  same  lactation 
period,  it  is  recommended  to  take  composite  samples  at 
the  intervals  given  below. 


For  spring  cows, 
For  summer  " 
For  fall  " 


FIRST  SAMPLE. 


6  weeks  after  calving. 

8        "       "  " 

8-10  "       "  " 


SECOND  SAMPLE. 


6|-7J  mos.  after  calving. 

6  -7       "        "  '« 

55-7       "        "  '' 


If  only  one  test  is  to  be  made,  approximately  correct  re- 
sults may  be  obtained  by  testing  the  milk  during  the  sixth 
month  from  calving,  in  case  of  spring  cows 5  during  the 
third  to  fifth  month  in  case  of  summer- calving  cows,  and 
during  the  fifth  to  seventh  month  for  fall- calving  cows. 

In  all  cases  composite  samples  of  the  milk  for  at  least 
four  days  should  be  taken  (165).  ^'  The  test  of  a  single 
sample,  drawn  from  a  single  milking  or  day,  will  not  of 
necessity,  or  indeed  usually  give  trustworthy  results. ' ' 

1  H.  B.  Gurler  in  Amei-iean  Dairying,  p.  18,  suggests  that  three  months 
after  calving  a  cow's  milk  may  be  weighed  for  a  week  and  a  composite 
sample  tested.  The  average  weight  of  butter  fat  produced  per  day  is  cal- 
culated and  this  average  figure  multiplied  by  252  or  the  number  of  days  in 
8.4  months.  It  is  assumed  that  a  cow  gives  milk  more  than  8.4  months 
and  the  quantity  produced  beyond  this  time  will  bring  the  production 
during  the  last  2.4  months  up  to  the  same  average  per  month  as  in  the 
first  six  months. 

2  Sixth  report,  1882,  p.  106;  Ninth  report,  1895,  p.  176. 


Testing  Milk  on  the  Farm.  139 

b.  As  to  quantity  of  milk  produced.  The  milk  may  be 
weighed  for  four  days  in  the  middle  of  the  month,  and 
the  entire  month's  yield  obtained  with  considerable 
accuracy  (barring  sickness  and  drying  off),  by  multiply- 
ing the  sum  by  7,  7|  or  7f,  according  to  the  number  of 
days  in  the  different  months.  The  weighing  is  most 
readily  done  by  means  of  a  spring  balance, 
the  hand  of  which  is  set  back  so  that  the 
empty  pail  brings  it  to  zero  (fig.  50).  If 
several  pails  are  to  be  used,  they  should 
first  be  made  to  weigh  the  same  by  putting 
a  little  solder  on  the  lighter  pails.  Milk 
scales  which  weigh  and  automatically  reg- 
ister the  yield  of  milk  from  twenty  cows 
have  been  placed  on  the  market,  but  no 
perfectly  satisfactory  device  of  this  kind 
has  yet  been  brought  out,  so  far  as  is  known 
to  the  authors. 

164.    Sampling    milk    of   single   cows.      In 

Fig.  50.     Milk 

Scale.  sampling  the  milk  of  single  cows,  all  the 
milk  obtained  at  the  milking  must  be  carefully  mixed, 
by  pouring  it  from  one  vessel  to  another  a  few  times,  or 
stirring  it  thoroughly  by  means  of  a  dipper  moved  up 
and  down,  as  well  as  horizontally,  in  the  pail  or  can  in 
which  it  is  held;  the  sample  for  testing  purposes  is  then 
taken  at  once.  A  correct  sample  of  a  cow's  milk  cannot 
be  obtained  by  milking  directly  into  a  small  bottle  from 
one  teat,  or  by  filling  the  bottle  with  a  little  milk  from 
each  teat,  or  by  taking  some  of  the  first,  middle  and  last 
milk  drawn  from  the  udder.  Such  samples  cannot  pos- 
sibly represent  the  quality  of  the  milk  of  one  entire  milk- 


140  Testing  Milk  and  Its  Products. 

ing,  since  there  is  as  much  difference  bet  wen  the  first  and 
the  last  portions  of  a  milking,  as  between  milk  and  cream.  ^ 
Lack  of  care  in  taking  a  fair  sample  is  the  cause  of  many 
surprising  results  obtained  in  testing  milk  of  single  cows. 
165.  ^yhen  a  cow  is  to  be  tested,  she  should  be  milked 
dry  the  last  milking  previous  to  the  day  when  the  test  is 
to  be  made.  The  entire  quantity  of  milk  obtained  at  each 
milking  is  mixed  and  sampled  separately.  On  account  of 
the  variation  in  the  composition  of  the  milk,  a  number  of 
tests  of  successive  milkings  must  be  made.  As  this  in- 
volves considerable  labor,  the  plan  of  taking  composite 
samples  is  preferable;  the  method  of  composite  sampling 
and  testing  is  explained  in  detail  under  the  second  sub- 
division of  Chapter  X  (176) ;  suffice  it  here  to  say  that  the 
method  followed  in  case  of  single  cows'  or  herd  milk  is 
to  take  about  an  ounce  of  the  thoroughly  mixed  milk  of 
each  milking;  this  is  placed  in  a  pint  or  quart  fruit  jar 
containing  a  small  quantity  of  some  preservative,  prefer- 
ably about  one-half  a  gram  (8  grains)  of  powdered  potas- 
sium bi-chromate.  If  a  number  of  composite  samples  of 
the  milk  of  single  cows  are  taken,  each  jar  should  be 
labeled  with  the  number  or  name  of  the  particular  cow. 
Composite  tests  are  generally  taken  for  four  days  or  for 
a  week.  If  continued  for  a  week,  the  jars  will  contain 
at  the  end  of  this  time  a  mixture  of  the  milk  of  fourteen 
milkings.  The  composite  sample  is  then  carefully 
mixed  by  pouring  it  gently  a  few  times  from  one  jar  to  an- 
other, and  is  tested  in  the  ordinary  manner.  The  result 
of  this  test  shows  the  average  quality  of  the  milk  pro- 


1  Woll,  Handbook  for  Farmers  and  Dairymen,  p.  194;  Agricultural 
Science,  6,  pp.  540-42. 


Testing  Milk  on  the  Farm.  141 

duced  by  the  cow  during  the  time  the  milk  was  sampled. 

166.  As  the  amounts  as  well  as  the  quality  of  the  milk 
produced  by  single  cows  vary  somewhat  from  day  to  day 
and  from  milking  to  milking,  it  is  desirable  in  testing 
single  cows,  especially  when  the  test  includes  only  a  few 
days,  to  take  a  proportionate  part  (an  aliquot)  of  each 
milking  for  the  composite  test  sample.  This  is  easily  done 
by  means  of  a  Scovell  sampling  tube,  the  use  of  which 
is  explained  in  another  place  (180),  or  by  a  25  cc.  pi- 
pette divided  into  -^^  cc. ;  in  using  the  latter  apparatus  as 
many  cubic  centimeters  and  tenths  of  a  cubic  centimeter 
of  milk  are  conveniently  taken  each  time  for  the  com- 
posite sample  as  the  weight  of  milk  in  pounds  and  tenths 
of  a  pound  produced  by  the  cow.^ 

The  opinion  is  often  expressed  that  a  considerable  error 
is  introduced  by  measuring  out  milk  warm  from  the  cow 
for  the  Babcock  test,  since  milk  expands  on  being  warmed, 
and  a  too  small  quantity  is  obtained  in  this  manner.  By 
calculation  of  the  expansion  of  milk  between  different 
temperatures  it  is  found  that  1  cc.  of  milk  at  17.5°  C. 
(room  temperature)  will  have  a  volume  of  1.006289  cc. 
at  37°  C.  (blood-heat),  i.  e.,  an  error  of  less  than  . 03  per 
cent,  is  introduced  by  measuring  out  milk  of  ordinary 
quality  at  the  latter  temperature.  While  the  temperature 
has  therefore  practically  no  importance,  the  air  incorpo- 
rated in  the  milk  during  the  milking  process  will  introduce 
an  appreciable  error  in  the  testing,  and  samples  of  milk 
should  therefore  be  left  for  an  hour  or  more  after  milking 
before  the  t«st  samples  are  taken.  By  this  time  the  specific 
gravity  of  the  samples  can  also  be  correctly  taken  (113). 

1  Decker,  Wis.  experiment  station,  report  XVI. 


1-42 


Testing  Milk  and  Its  Products. 


167.  Size  of  the  testing  sample.  Four  ounces  is  a  suffi- 
cient quantity  for  a  sample  of  milk  if  it  is  desired  to  de- 
termine its  per  cent,  of  fat  only;  if  the  milk  is  to  be  tested 
with  a  lactometer,  when  adulteration  is  suspected,  as 
much  as  a  pint  is  needed  for  a  sample.  If  this  sample  of 
milk  is  put  into  a  bottle  and  carried  or  sent  away  from 
the  farm  to  be  tested,  the  bottle  should  be  filled  with  milk 
clear  up  to  the  cork  to  prevent  a  partial  churning  of 
butter  in  the  sample  during  transportation  (30). 

168.  Variations  in  herd  milk.  While  considerable  vari- 
ations in  the  quality  of  milk  of  single  cows  are  often  met 
with,  a  mixture  of  the  milk  of  several  cows,  or  of  a  whole 
herd  is  comparatively  uniform  from  day  today;  the  indi- 
vidual differences  tend  to  balance  each  other  so  that  vari- 
ations, when  they  do  occur,  are  less  marked  than  in  case 
of  milk  of  single  cows.  There  are,  however,  at  times 
marked  variations  also  in  the  test  of  herd  milk  on  suc- 
cessive days;  the  following  figures  from  the  dairy  tests 
conducted  at  the  World's  Columbian  Exposition  in  Chi- 
cago in  1893  illustrate  the  correctness  of  this  statement. 
The  test  included  twenty-five  Jersey  and  Guernsey  cows 
each  and  twenty- four  Shorthorn  cows. 

Tests  of  herd  milk  on  successive  days. 


DATE. 

Jersey. 

Guernsey. 

Shorthorn. 

July  16,  1893    

4.8  per  cent. 

5.0 

4.7 

4.6 

5.0 

4.6  per  cent. 

4.5 

4.4 

4.6 

4.5 

3.8  percent. 

3.8 

3.8         " 

July  17,  1893 

July  18,  1893 

July  19,  1898 

3.7         " 

July  20,  1893 

3.8         " 

Testing  Mill'  on  the  Farm.  143 

On  July  17,  1893,  the  mixed  milk  of  the  Jersey  cows 
tested  two-tenths  of  one  per  cent,  higher  than  on  the  pre- 
cediDg  day  5  the  Guernsey  herd  milk  tested  one-tenth  of 
one  per  cent,  lower,  while  the  Shorthorn  milk  did  not 
change  in  composition;  comparing  the  tests,  on  July  19 
and  20,  we  find  that  the  Jersey  and  Shorthorn  milk  tested 
four-tenths  and  one-tenth  of  one  per  cent,  higher,  respect- 
ively, on  the  latter  day  than  on  the  former,  and  the 
Guernsey  milk  tested  one-tenth  of  one  per  cent,  lower. 

169.  Ranges  in  variations  of  herd  milk.  According  to 
Fleischmann,^  the  composition  of  herd  milk  may  on  single 
days  vary  from  the  average  values  for  the  year  expressed 
in  per  cent,  of  the  latter,  as  follows: 

The  specific  gravity  (expressed  in  degrees)  may  go  above  or 
below  the  3'early  average  by  more  than  10  percent. 

The  per  cent,  of  fat  may  go  above  or  below  the  yearly  aver- 
age by  more  than  30  per  cent. 

The  per  cent,  of  total  solids  may  go  above  or  below  the  year- 
ly average  by  more  than  14  per  cent. 

The  per  cent,  of  solids  not  fat  may  go  above  or  below  the 
yearly  average  by  more  than  10  per  cent. 

To  illustrate,  if  the  average  test  of  a  herd  during  a  whole 
period  of  lactation  is  4.0  per  cent.,  the  test  on  a  single  day  may 
exceed  4.0-|-iVo  X  4.0=5.2,  ormay  go  below  2.8  per  cent.,  (viz., 
4.0— tW  X  4.0);  if  the  average  specific  gravity  is  1.031  (lacto- 
meter degrees,  31'-)  the  specific  gravity  of  the  milk  on  a  single 
day  may  vary  between  1.0279  and  1.0341  (31  +  iVo  X  31=34.1; 
31 -tVoX  31=27.9). 

170.  Influence  of  heavy  grain-feeding  on  the  quality  of 
milk.  If  cows  are  not  starved  or  underfed,  an  increase 
in  the  feeding  ration  will  not  materially  change  the  rich- 
ness of  the  milk  produced,  as  has  been  shown  by  careful 

1  Book  of  the  Dairy,  p.  32. 

2  See  page  94. 


144  Testing  Milk  and  Its  Products. 

feeding  experiments  conducted  under  a  great  variety  of 
conditions  and  in  many  countries.  Cows  that  are  fairly 
well  fed  will  almost  invariably  give  more  milk  when 
their  rations  are  increased,  but  the  milk  will  remain  of 
about  the  same  quality  after  the  first  few  days  are  passed 
as  before  this  time,  provided  the  cows  are  in  good  health 
and  under  normal  conditions.  Any  change  in  the  feed 
of  cows  will  usually  bring  about  an  immediate  change  in 
the  fat  content  of  the  milk,  as  a  rule  increasing  it  to  some 
extent,  but  in  the  course  of  a  few  days,  when  the  cows 
have  become  accustomed  to  their  new  feed,  the  fat  content 
of  the  milk  will  again  return  to  its  normal  amount. 

171.  The  records  of  the  cows  included  in  the  feeding 
experiment  at  the  Illinois  station,  to  which  reference  has 
been  made  on  p.  183,  furnish  illustrations  as  to  the  effect 
of  heavy  feeding  on  the  quality  of  milk.  The  feed,  as 
well  as  the  milk  of  the  cows,  was  weighed  each  day  of 
the  experiment.  During  the  month  of  December  each 
cow  was  fed  a  daily  ration  consisting  of  10  lbs.  of  tim- 
othy hay,  20  lbs.  of  corn  silage  and  2  lbs.  of  oil  meal; 
the  table  on  p.  134  shows  that  cow  No.  3  produced  on 
this  feed  an  average  of  12.1  lbs.  of  milk,  testing  3.8  per 
cent,  of  fat.  In  January  the  grain  feed  was  gradually 
increased  until  the  ration  consisted  of  12  lbs.  of  timothy 
hay,  8  lbs.  of  corn  and  cob  meal,  4  lbs.  of  wheat  bran  and 
4  lbs.  of  oil  meal.  All  the  cows  gained  in  milk  on  this 
feed;  cow  No.  3  thus  gave  an  average  of  4  lbs.  more 
milk  per  day  in  January  than  in  December,  but  the  aver- 
age test  of  her  milk  was  3. 7  per  cent.,  or  one-tenth  of  one 
per  cent,  lower  than  during  the  preceding  month.  The 
heavy  grain  feeding  was  continued  through   February 


Testing  Milk  on  the  Farm.  145 

and  March,  when  it  reached  12  fts.  of  timothy  hay,  12 
lbs.  of  corn  and  cob  meal,  6  fts.  of  wheat  bran  and  6  lbs. 
of  oil  meal  per  day.  The  records  show  that  the  flow  of 
milk  kept  up  to  16  lbs.  per  day  in  February  in  case  of 
this  cow,  but  fell  to  14  lbs.  in  March  and  April,  the 
average  test  of  the  milk  being,  in  February  3.6,  in  March 
3.8,  and  in  April  4.0  per  cent.  The  milk  was,  therefore, 
somewhat  richer  in  April  than  in  December,  but  not 
more  so  than  is  found  normally,  owing  to  the  progress  of 
the  period  of  lactation. 

172.  Influence  of  pasture  on  the  quality  of  milk.  On 
May  1,  the  cows  were  given  luxuriant  pasture  feed  and 
no  grain;  a  slight  increase  in  the  average  amount  of  milk 
produced  per  day  followed,  with  a  reduction  in  the  test, 
this  being  3.8  per  cent,  the  same  as  in  December. 

During  all  these  changes  of  feed,  there  was,  therefore, 
not  much  change  in  the  richness  of  the  milk,  while  the 
flow  of  milk  was  increased  by  the  heavy  grain  feeding 
for  several  months,  as  well  as  by  the  change  from  grain- 
feeding  in  the  barn  to  pasture  feed  with  no  grain. ^ 

173.  The  increase  which  has  often  been  observed  in  the 
amount  of  butter  produced  by  a  cow,  as  a  result  of  a 
change  in  feed,  doubtless  as  a  rule  comes  from  the  fact 
that  more,  but  not  richer  milk  is  produced.  The  quality 
of  milk  which  a  cow  produces  is  as  natural  to  her  as  is 
the  color  of  her  hair  and  is  not  materially  changed  by 
any  special  system  of  normal  feeding.' 

1  For  further  data  on  this  point,  see  Cornell  (N.  Y.)  exp.  sta.,  bulletins 
13,  '22,  3C  and  49;  JS.  D.  exp.  sta.,  bull.  16;  Kansas  exp.  sta.,  report,  1888; 
Hoard's  Dairyman,  1896,  pp.  924-5. 

2  On  this  point  numerous  discussions  have  in  recent  years  taken  place 
in  the  agricultural  press  of  this  and  foreign  countries,  and  the  subject  has 
been  under  debate  at  nearly  every  gathering  of  farmers  where  feeding 

1 


146  Testing  Milk  and  Its  Products. 

174.  Method  of  improving  the  quality  of  milk.  The  qual- 
ity of  the  milk  produced  by  a  herd  can  generally  be  im- 
proved by  selection  and  breeding,  i.  e.,  by  disposing 
of  the  cows  giving  poor  milk,  say  below  3  per  cent,  of 
fat,  and  by  breeding  to  a  pure- bred  bull  of  a  strain 
that  is  known  to  produce  rich  milk.  This  method  can- 
not work  wonders  in  a  day,  or  even  in  a  year,  but  it  is 
the  only  certain  way  we  have  to  improve  the  quality  of 
the  milk  produced  by  our  cows. 

It  may  be  well  in  this  connection  to  call  attention  to 
the  fact  that  the  quality  of  the  milk  which  a  cow  pro- 
duces is  only  one  side  of  the  question;  the  quantity  is 
another,  and  an  equally  important  one.  Much  less  dissat- 
isfaction and  grumbling  about  low  tests  among  patrons  of 
creameries  and  cheese  factories  would  arise  if  this  fact 
was  more  generally  kept  in  mind.  A  cow  giving  3  per 
cent,  milk  should  not  be  condemned  because  her  milk 
does  not  test  5  per  cent. ;  she  may  give  twice  as  much  milk 

proble  lis  liave  been  considered.  Many  farmers  are  firm  in  their  belief 
that  butter  fat  can  be  "fed  into"  the  milk  of  ;t  cow,  and  would  take  excep- 
tion to  the  conclusion  drawn  in  the  preceding.  The  results  of  careful  in- 
vestigations by  our  best  dairy  authorities  point  conclusively,  however,  in 
the  direction  stated,  and  the  evidence  on  this  point  is  overwhelmingly 
against  the  opinion  that  the  fat  content  of  the  milk  can  be  materially  and 
for  any  length  of  time  increased  by  changes  in  the  system  of  feeding.  The 
most  conclusive  evidence  in  tli's  line  is  perhaps  the  Danish  co-operative 
cow-feeding  experiments,  conducted  during  the  nineties  with  over  2,000 
cows  in  all.  The  conclusion  arrived  at  by  the  director  of  the  Copen- 
hagen experiment  station,  under  whose  supervision  the  experiments  have 
been  conducteJ,  has  been  repeatedly  stated  in  the  published  reports  of  the 
station:  that  the  changes  of  feed  made  in  the  different  lots  of  cows  included 
in  the  experiments  have  had  practically  no  influence  on  the  chemical 
composition  (the  fat  content  I  of  the  i  ilk  produced  In  these  experiments 
grain  feeds  have  been  fed  ;igainst  roots,  against  oil  cake,  and  against  wheat 
bran  or  shorts;  grain  and  oil  cake  have  furthermore  been  fed  against  roots, 
and  roots  have  been  given  as  an  additional  feed  to  the  standard  rations 
tried,— ill  all  cases  with  practically  negative  results  so  far  as  changes  in 
the  fat  contents  of  the  milk  produced  are  concerned. 


Testing  Milk  on  the  Farm.  147 

per  day  as  a  5  per  cent,  cow,  and  will  therefore  produce 
considerably  more  butter  fat.  The  point  whether  or  not 
a  cow  is  a  persistent  milker  is  also  of  primary  import- 
ance; a  production  of  300  lbs.  of  butter  fat  during  a 
whole  period  of  lactation  is  a  rather  high  dairy  standard, 
but  one  reached  by  many  herds,  even  as  the  average  for 
all  mature  cows  in  the  herd.  It  should  be  remembered 
that  a  high  production  of  butter  fat  in  the  course  of  the 
whole  period  of  lactation  is  of  more  importance  than  a 
very  high  test. 


CHAPTEE  X. 
COMPOSITE  SAMPLES  OF  MILK. 

175.  Shortly  after  milk  testing  had  been  introduced  to 
some  extent  in  creameries  and  cheese  factories,  it  was 

suggested  by  Patrick, 


%- 


J 


#M^ 


,\ 


itfimt:    . 


'^^' 

a 


then  of  the  Iowa  ex- 
periment station,  ^that 
a  great  saving  in  labor 
without  affecting  the 
accuracy  of  the  results 
could  be  obtained  by 
mixing  the  daily  sam- 
ples of  milk  from  one 
source,  and  testing  this 
mixture  instead  of 
each  sample  contribu- 
ting thereto.  Such  a 
mixture  is  called  a 
composite  sample.  The 
usual  methods  of  tak- 
ing such    samples  at 

FIG.  51.    Taking  test  samples  at  in-take.        creameries  and  chcCSC 

factories  during  the  past  few  years  have  been  as  follows: 
176.  Methods  of  taking  composite  samples,  a.  Ise  of 
tin  dipper.  Either  pint  or  quart  Mason  fruit  jars,  or  milk 
bottles  provided  with  a  cover,  are  used  for  receiving  the 
daily  samples.     One  of  these  jars  is  supplied  for  each 


1  Bulletin  No.  9,  May  1890. 


Composite  Samples  of  Millc.  149 

patron  of  the  factory  and  is  labeled  with  his  name  or 
number.  A  small  quantity  of  preservative  (bi-chromate 
of  potash,  bi-chlorid  of  mercury,  etc.,  see  188)  is  added 
to  each  jar;  these  are  placed  on  shelves  or  somewhere 
within  easy  reach  of  the  operator  who  inspects  and 
weighs  the  milk  as  it  is  received  at  the  factory.  When 
all  the  milk  delivered  by  a  patron  is  poured  into  the 
weighing  can  and  weighed,  a  small  portion  thereof, 
usually  about  an  ounce,  is  put  into  the  jar  labeled  with 
the  name  or  number  of  the  patron.  The  samples  are 
conveniently  taken  by  means  of  a  small  tin  dipper  hold- 
ing about  an  ounce.  This  sampling  is  continued  for  a 
week,  ten  days,  or  sometimes  two  weeks,  a  portion  of 
each  patron's  milk  being  added  to  his  particular  jar 
every  time  he  delivers  milk.  A  test  of  these  composite 
samples  takes  the  place  of  separate  daily  tests  and  gives 
accurate  information  regarding  the  average  quality  of  the 
milk  delivered  by  each  patron  during  the  period  of 
sampling.  The  weight  of  butter  fat  which  each  patron 
brought  to  the  factory  in  his  milk  during  this  time,  is 
obtained  by  multiplying  the  total  weight  of  milk  deliv- 
ered during  the  sampling  period  by  the  test  of  the 
composite  sample,  dividing  the  product  by  100. 

177.  This  method  of  taking  composite  samples  has  been 
proved  to  be  practically  correct.  It  is  absolutely  correct 
only  when  the  same  weight  of  milk  is  delivered  daily  by 
the  patron.  If  this  is  not  the  case,  the  size  of  the  various 
small  samples  should  bear  a  definite  relation  to  the  milk 
delivered;  one  sixteen- hundredth,  or  one  two-thousandth 
of  the  amount  of  milk  furnished  should,  for  instance,  be 
taken  for  the  composite  sample  from  each  lot  of  milk. 


150  Testing  Milk  and  Its  Products. 

This  can  easily  be  done  by  means  of  special  sampling 
devices  (see  179  et.  seq.  )•  As  the  quantities  of  the  milk 
delivered  from  day  to  day  by  each  patron  vary  but  little, 
perhaps  not  exceeding  10  per  cent,  of  the  milk  delivered, 
the  error  introduced  by  taking  a  uniform  sample,  e.  g. , 
an  ounce  of  milk,  each  time  is,  however,  too  small  to  be 
worth  considering  in  factory  work,  and  the  method  of 
composite  sampling  described  is  generally  adopted  in 
separator  creameries  and  cheese  factories,  where  the 
payment  of  the  milk  is  based  on  its  quality. 

178.  By  this  method  of  composite  sampling  each  lot  of 
rich,  medium  or  thin  milk  receives  due  credit  for  the 
amount  of  butter  fat  which  it  contains,  and  errors  that 
might  arise  from  testing  only  one  day's  milk  at  irreg- 
ular intervals  are  avoided.  In  order  to  obtain  reliable 
results  by  composite  sampling  it  is  essential  that  each 
lot  of  milk  sampled  shall  be  sweet  and  in  good  condition, 
containing  no  lumps  of  curdled  milk  or  butter  granules. 
The  milk  is  of  course  always  evenly  mixed  before  the 
sample  is  taken. 

179.  b.  Drip  sample.  Composite  samples  are  sometimes 
taken  at  creameries  and  cheese  factories  by  collecting  in 
a  small  dish  the  milk  that  drips  through  a  fine  hole  or 
tube  placed  in  the  conductor  spout  through  which  the 
milk  runs  from  the  weighing  can  to  the  receiving  vat  or 
tank.  A  small  portion  of  the  drip  collected  each  day  is 
placed  in  the  composite  sample  jar,  or  the  quantity  of 
drip  is  regulated  so  that  all  of  it  may  be  taken.  In  the 
latter  case  the  quantity  of  milk  delivered  will  enter  into 
the  composite  sampling  as  well  as  its  quality,  and  the 
sample  from,  say  200  lbs.  of  milk,  will  be  twice  as  large 
as  the  sample  from  100  lbs.  of  milk. 


Composite  Samples  of  Milk.  151 

Where  it  is  desiredtovarylhesizeof  the  samples  accord- 
ing to  the  quantity  of  milk  delivered  from  day  to  day,  it  is 
necessary  to  adopt  the  method  of  collecting  drip  samples, 
just  explained, or  to  make  use  of  special  sampling  devices, 
like  the  ''milk  thief,"  the  Scovell,  or  the  Equity  sampling 
tube.  The  principle  of  these  tubes  is  the  same,  and  it 
will  be  sufficient  to  describe  here  only  the  latter  two. 

150.  c.  The  Scovell  sampling  tube.  This  convenient 
device  for  sampling  milk  ^  (fig.  52)  consists  of  a  drawn 
copper  or  brass  tube,  one-half  to  one  inch  in 
diameter;  it  is  open  at  both  ends,  the  lower  end 
sliding  snugly  in  a  cap  provided  with  three 
elliptical  openings  at  the  side,  through  which  the 
milk  is  admitted.  The  milk  to  be  sampled  is 
poured  into  a  cylindrical  pail,  or  the  factory 
weighing  can,  and  the  tube,  with  the  cap  set  so 
that  the  apertures  are  left  open,  is  lowered  into 
the  milk  until  it  touches  the  bottom  of  the  can. 
The  tube  will  be  filled  instantly  to  the  level  of 
the  milk  in  the  can  and  is  then  pushed  down 
against  the  bottom  of  the  can,  thereby  closing  the 
apertures  of  the  cap  and  confining  within  the  tube 
a  column  of  milk  representing  exactly  the  quality 
of  the  milk  in  the  can  and  forming  an  aliquot  part 
thereof.  The  milk  in  the  sampling  tube  is  then 
emptied  into  the  composite  sample  jar  by  turn- 
ing the  tube  upside  down.  fig^  52. 

151.  If  the  diameter  of  the  sampling  pail  used    scoveii 

milk  gamp- 
is  8  inches,  and  that  of  the  sampling  tube  J  inch   img  tube, 

(these  dimensions  will  be  found  convenient  in  sampling 


1  Kentucky  experiment  station,  Sth  report,  pp.  xxvi-xxxii. 


152  Testing  Milk  and  Its  Products. 

milk  from  siugle  cows),  then  the  quautity  of  milk 
secured  in  the  tube  will  always  stand  in  the  ratio  to  that 
of  the  milk  in  the  pail,  of  (J)'  to  8'/  that  is,  as  1  to 
256,  no  matter  how  much  or  how  little  milk  there  is  in 
the  pail,  the  sample  will  represent  ^io  P^^t  of  the  milk. 
For  composite  sampling  of  the  milk  of  single  cows,  this 
proportion  will  prove  about  right;  if  more  milk  is  wanted 
for  a  sub  sample,  dip  twice,  or  pour  the  milk  to  be 
sampled  into  a  can  of  smaller  diameter.  If  the  mixed 
milk  from  a  number  of  cows  is  to  be  sampled,  a  wider 
sampling  can  be  used.  By  adjusting  the  diameters  of 
the  tube  and  the  can,  any  desired  proportion  of  milk  can 
be  obtained  in  the  sample. 

For  factory  sampling,  with  a  weighing  can,  26  inches 
in  diameter,  a  tube  three-quarters  of  an  inch  in  diameter 
will  be  found  of  proper  dimensions. 

In  using  any  one  of  these  tubes,  the  size  of  the  sample 
is  regulated  by  the  amount  of  milk  in  the  sampling  can, 
as  the  milk  always  rises  to  the  same  height  in  the  tube 
as  in  the  can.  In  all  cases  cylindrical  sampling  cans  must 
be  used. 

182.  The  sampling  tube  will  furnish  a  correct  sample 
of  the  milk  in  the  can,  even  if  this  has  been  left  standing 
for  some  time;  it  is  better,  however,  to  take  out  the  sam- 
ple soon  after  the  milk  has  been  poured  into  the  can,  as 
the  possible  error  of  cream  adhering  to  the  sides  of  the 
sampling  tube  is  then  avoided. 

183.  The  accuracy  of  the  sampling  of  milk  by  means 
of  the  Scovell  tube  was  proved  beyond  dispute  in  the 

1  The  contents  of  a  cylinder  are  represented  by  the  formula  7ri2h,  r  be- 
ing the  radius  of  the  cylinder,  and  h  its  height.  The  relation  between  two 
cylinders  of  the  same  height,  the  radii  of  which  are  R  and  r,  is  therefore 
as  7rR2h  to  7rr2h,  or  as  R2  to  r2. 


Composite  Samples  of  Mill:  153 

breed  tests  conducted  at  the  World's  Columbian  Exposi- 
tion in  1893,  in  which  tests  this  method  was  adopted  for 
sampling  the  milk  produced  by  the  single  cows  and  the 
different  herds.  ^  The  data  obtained  in  these  breed  tests 
also  furnish  abundant  proof  of  the  accuracy  of  the  Bab- 
cock  test. 

184.  d.  The  Equity  milk  sampler.  This  sampling  device 
is  the  invention  of  Messrs.  Joseph  Kolarik  and  Carl 
Werder.  A  half  inch  brass  tube,  closed  by  a  disc  fastened 
to  a  rod  within  and  kept  in  place  by 
a  spring  at  the  top,  is  held  in  upright 
position  inside  of  the  weigh  can  by 
the  guide  piece  clamped  to  the  rim  of 
the  can.  The  operation  is  simple.  The 
milk  is  poured  into  the  weigh  can, 
the  tube  is  lifted  until  its  bottom  end  r-^^K^ 
is  clear  of  the  milk,  a  slight  pressure  /  J^  ^ 
of  the  finder  at  the  top  opens  the  tube, 

Fm.53.  ^  ^     f  ;         Fig.  54. 

Takingthe   and  SO  Opened  it  is  let  down  through    Discharging 

sample,    ^j^^  ^^^^^  closing  of  itsclf  as  it  touches     ^^^^  J^^- 
the  bottom  of  the  can.     The  sample  of  milk  is  now  in 
the  tube   and   cannot  leak    out  or  be  lost.     The  com- 
posite sample  bottle   is  held  under  the  spout  and    the 

tube  raised  as  high  as  the  guide  will  permit.  The 
construction  of  this  guide  is  such  that  the  tube,  when 
raised  to  its  level,  discharges,  automatically,  into  the  test 
jar  through  the  spout  (see  figs.  53  and  54). 

IS5.  e.  Composite  sampling  with  a  *<one-third  sample 
pipette.'*     Milk  is  sometimes  sampled  directly  from  the 

1  Kentucky  experiment  station,  8th  report,  pp.  xxx-xxxi.  Another 
form  of  a  milk  sampling  tube  in  use  at  the  Iowa  experiment  station  was 
described  and  illustrated  by  Mr.  Eckles  in  Breeder's  Gazette,  May  19, 1897- 


154 


Testing  Milk  and  Its  Products. 


weighing  can  into  the  Babcock  test  bottle  by  means  of  a 
pipette  holding  5.87  cc,  which  is  one- third  the  size  of 
the  regular  pipette.  This  quantity  is  measured  into  the 
test  bottle  from  three  successive  lots  of  milk  from  the 
same  patron  and  the  test  then  made  in  the  ordinary 
manner.  In  this  way  one  test  shows  the  average  com- 
position of  the  milk  delivered  during  three  successive 
days  or  deliveries.  When  this  method  is  adopted,  as 
many  test  bottles  are  provided  as  there  are  patrons; 
there  is  no  need  of  using 
any  preservatives  for  the 
milk  in  this  case.  Fig. 
55  shows  a  convenient 
rack  for  holding  the  test 
bottles  used  in  compos- 
ite sampling  with  a  ^'one- 
third  sample  pipette. ' ' 

Accurate  results  can  be 
obtained  by  this  method 
of  sampling,  if  care  is 
taken  in  measuring  out 
the  milk,  and  if  it  is  not 
frozen  or  contains  lumps 
of  cream.  It  is  doubtful  if  the  method  has  any  advan- 
tage over  the  usual  method  of  composite  sampling.  If 
milk  is  delivered  daily  and  each  lot  is  sampled  with  the 
one-third  pipette,  twice  or  three  times  the  number  of  tests 
are  required  as  when  composite  samples  are  taken  in  jars 
and  tested  once  every  week  or  ten  days.  This  method 
furthermore  takes  a  little  more  time  in  the  daily  sampl- 
ing than  the  other,  as  the  quantity  of  milk  must  be  meas- 


FiG,  55.    Test-bottle  rack  for  use  in 
creameries  and  ciieese  faitoriep. 


Composite  Samples  of  Mill: 


155 


ured  out  accurately  each  time.  If  the  test  bottle  is  acci- 
dently  broken  or  some  milk  spilled,  the  opportunity  of 
ascertaining  the  fat  content  of  the  milk  delivered  during 
the  three  days  is  lost;  if  a  similar  accident  should  occur 
in  testing  composite  samples  collected  in  jars,  another 
test  can  readily  be  made. 

IS6.  Accuracy  of  the  described  methods  of  sampling. 
An  experiment  made  at  the  Wisconsin  Dairy  School  may 
here  be  cited,  showing  that  concordant  results  will  be 
obtained  by  the  use  of  the  drip  sampling  method  and  the 
Scovell  tube.  Two  composite  samples  were  taken  from 
fifty  different  lots  of  milk,  amounting  to  about  6,000  fbs. 
in  the  aggregate.  One  sample  was  taken  of  the  drip 
from  a  hole  in  the  conductor  spout  through  which  the 
milk  passed  from  the  weighing  can;  the  other  was  taken 
from  the  weighing  can  by  means  of  a  Scovell  sampling 
tube.  The  following  percentages  of  fat  were  found  in 
each  of  these  samples:  ^ 


Drip  composite  sample 

Scovell  tube  composite  sample. 


Babcock  test. 


4.0  per  cent. 
4.0  per  cent. 


Gravimetric 
analysis. 


4  04  percent. 
4.06  percent. 


Preservatives  for  Composite  Samples. 
187.  When  milk  is  kept  any  length  of  time  under  ordi- 
nary conditions,  it  will  soon  turn  sour  and  become  lop- 
pered,  and  further  decomposition  shortly  sets  in,  which 
renders  the  sampling  of  the  milk  both  difficult  and  unsatis- 
factory (19).  The  changes  which  occur  when  milk  sours 
are  due  to  the  formation  of  lactic  acid  by  the  action  of 
bacteria  on  milk  sugar;  the  acid  coagulates  the  casein  of«the 


1  See  also  189  et  seq. 


156  Testing  Milk  and  Its  Products. 

milk,  but  does  not  destroy  or  attack  the  butter  fat  (32). 
The  period  during  which  milk  will  remain  in  an  appar- 
ently sweet  or  fresh  condition  varies  with  the  temperature 
at  which  it  is  kept,  and  with  the  cleanliness  of  the  milk. 
It  will  not  generally  remain  sweet  longer  than  two  days  at 
the  outside,  at  ordinary  summer  or  room  temperature. 

In  order  to  preserve  composite  samples  of  milk  in  a 
proper  condition  for  testing,  some  chemical  which  will 
check  or  prevent  the  fermentation  of  the  milk  must  be 
added  to  it.  A  number  of  substances  have  been  proposed 
for  |his  purpose. 

188.  Bi-chromate  of  potash.  This  preservative  is,  in 
the  opinion  of  the  authors,  to  be  preferred,  on  account  of 
its  relative  harmlessness,  its  cheapness  and  efficiency. 
The  bichromate  method  for  preserving  samples  of  milk 
was  proposed  by  Mr.  J.  A.  Alen,  city  chemist  of  Gothen- 
burg, Sweden,  in  1892,^  and  has  been  generally  adopted 
in  dairy  regions  in  this  country  and  abroad.  While  not 
perfectly  harmless,  the  bichromate  is  not  a  violent  poison 
like  other  chemicals  proposed  for  this  purpose,  and  no 
accidents  are  liable  to  result  from  its  use;  at  least  none 
have  been  known  to  the  writers  to  occur  during  the  years 
that  it  has  been  used  in  creameries  or  dairies  as  a  pre- 
serving agent. 

189.  The  quantity  of  bi-chromate  necessary  for  preserv- 
ing half  a  pint  to  a  pint  of  milk  for  a  period  of  one  or 
two  weeks  is  about  one-half  gram  (nearly  8  grains).  As 
there  are  about  900  half-grams  in  a  pound,  this  quantity 
will  suffice  for  nine  weeks  in  a  creamery  having  one 
hifndred  patrons,  if  tests  are  made  once  a  week,  or  for 
three  months  (90  days)  if  tests  are  made  every  ten  days. 

1  Biedermann's  Centralblatt,  1892,  p.  549. 


Composite  Sample  of  Milk.  157 

According  to  Winton  and  Ogden/  a  .22-inch  pistol 
cartridge  shell  cut  to  J  inch  long,  or  a  .32 -inch  calibre 
shell  cut  to  J  inch  long,  when  loosely  filled,  will  hold 
enough  powdered  bi  chromate  to  preserve  J  pint,  and  a 
.32-inch  calibre  shell  cut  to  J  inch  long  will  hold  enough 
to  preserve  one  pint.  These  shells  may  be  conveniently 
handled  by  soldering  to  them  a  piece  of  stiff  wire  which 
serves  as  a  handle.  The  amount  of  bi-chromate  placed 
in  each  composite  sample  jar  would  fill  about  half  the 
space  representing  one  per  cent,  in  the  neck  of  a  Bab- 
cock  milk  test  bottle. 

190.  The  first  portions  of  milk  added  to  the  composite 
samplejars  containing  the  specified  amount  of  bi-chro- 
mate will  be  colored  almost  red,  but  as  more  milk  is 
added,  day  by  day,  its  color  will  become  lighter  yellow. 
The  complete  sample  should  have  a  light  straw  color; 
such  samples  are  most  easily  mixed  with  acid  when 
tested.  If  more  bi- chromate  is  used,  the  solution  of 
the  casein  in  the  acid  is  rendered  difficult  and  requires 
persistent  shaking.  Bi- chromate  can  be  bought  at  drug 
stores  or  from  dairy  supply  dealers  at  about  30  cents  a 
pound  and  will  cost  about  25  cents  a  pound  at  wholesale. 
Powdered  bi-chromate  of  potash  should  be  ordered,  and 
not  crystals,  as  the  latter  dissolve  only  slowly  in  the 
milk.  Farrington's  bi-chromate  tablets  contain  the  cor- 
rect quantity  of  preservative  for  a  quart  sample,  and  will 
be  found  convenient. 

I9L  Other  preservatives  for  composite  samples.  Among 
other  substances  recommended  for  use  in  butter  or  cheese 
factories  as  milk  preservatives  for  composite  samples  are 

1  Connecticut  experiment  station,  report  for  1884,  p.  222. 


158  Testing  Milk  and  Its  Products. 

formalin,  boracic-acid  compounds,  chloroform,  carbon 
bi-sulfid,^  copper  ammonium  sulfate,  sodium  fluorid, 
ammonia  glycerin  (sp.  gr.,  1.031),  and  mixtures  contain- 
ing mercuric  chlorid  (corrosive  sublimate)  with  anilin 
color  (rosanilin).'  The  coloring  matter  in  the  latter 
compounds  is  added  to  give  a  rose  color  to  the  sample 
preserved,  thus  showing  that  the  milk  is  not  fit  for  con- 
sumption; the  bichromate  giving  naturally  a  yellow  color 
to  the  milk,  renders  unnecessary  the  addition  of  any 
special  coloring  matter. 

None  of  the  substances  mentioned  are  as  cheap  as  bi- 
chromate or  more  effective  for  factory  purposes  when  the 
milk  is  to  be  kept  not  to  exceed  two  or  three  weeks.  The 
compounds  containing  corrosive  sublimate  are  violent  poi- 
sons and  must  always  be  handled  with  the  greatest  care, 
lest  they  get  into  the  hands  of  children  or  persons  unfamil- 
iar with  their  poisonous  properties;  they  will  preserve  the 
milk  longer  than  bichromate  when  applied  in  sufficient 
quantities,  but  for  factory  use  the  latter  is  amply  effective 
and  has,  as  already  stated,  the  advantage  in  several 
respects.  During  late  years  corrosive  sublimate  tablets 
have,  however,  come  into  general  use  in  factories. 

192.  Care  of  composite  samples.  The  composite  sam- 
ple jars  should  be  kept  covered  to  prevent  loss  by  evapor- 
ation, and  in  a  cool,  dark  place,  or  at  least  out  of  direct  sun- 
light; the  chromic  acid  formed  by  the  reducing  influence 
of  light  on  chromate  solutions  produces  a  leathery  cream 
which  is  very  difficultly  dissolved  in  sulfuric  acid. 


1  Delaware  experiment  station,  eighth  report,  1896,  which  also  see  for 
trials  with  a  large  number  of  different  preservatives. 

2  Iowa  experiment  station,  bulletins  9, 11,  32. 


Oomposite  Sample  of  Milk.  159 

A  coating  of  white  shellac  has  been  suggested  to  protect 
the  labels  of  the  composite  sample  jars.  The  shellac  is  ap- 
plied after  the  names  of  the  patrons  have  been  written  on 
the  labels,  and  when  these  have  been  put  on  the  jars. 
Gummed  labels,  1x2^  inches,  answer  this  purpose  well. 

In  keeping  the  milk  from  day  to  day,  care  should  be 
taken  that  the  cream  forming  on  the  milk  does  not  stick 
to  the  sides  of  the  jars  in  patches  above  the  level  of  the 
milk.  Unless  the  daily  handling  of  the  jars  and  the 
addition  of  fresh  portions  of  milk  be  done  with  sufficient 
care,  the  cream  will  become  lumpy  and  will  dry  on  the 
sides  of  the  jars.  In  some  cases  it  is  nearly  impossible 
to  evenly  distribute  this  dried  cream  through  the  entire 
sample  so  as  to  make  the  composite  sample  a  true  repre- 
sentative of  the  different  lots  of  milk  from  which  it  has 
been  taken. 

193.  Every  time  a  new  portion  of  milk  is  added  to  the 
jar  this  should  be  given  a  gentle  horizontal  rotary  mo- 
tion, thereby  mixing  the  cream  already  formed  in  the 
jar  with  the  milk  and  rinsing  off  the  cream  sticking  to 
its  side.  This  manipulation  also  prevents  the  surface  of 
the  milk  from  becoming  covered  with  a  layer  of  partially 
dried  leathery  cream. 

Composite  samples  having  patches  of  dried  cream  on 
the  inside  of  the  jar  are  the  result  of  carelessness  or  ignor- 
ance on  the  part  of  the  operator.  If  proper  attention  is 
given  to  the  daily  handling  of  the  composite  samples,  the 
cream  formed  in  the  jars  can  without  difficulty  again  be 
evenly  mixed  with  the  milk. 

194.  Fallacy  of  averaging  percentages.  A  composite 
sample  of  milk  should  represent  the  average  quality  of 


160 


Testing  Milk  and  Its  Products. 


the  various  lots  of  milk  of  which  it  is  made  up.  This 
will  invariably  be  true  if  a  definite  aliquot  portion  or 
fraction  of  the  different  lots  of  milk  is  taken.  If  the 
weights  of,  say  ten  different  lots  of  milk,  are  added  to- 
gether and  the  sum  divided  by  ten,  the  quotient  will 
represent  the  average  weight  per  lot  of  milk,  but  an 
average  of  the  tests  of  the  different  lots  obtained  in  this 
way  may  not  be  the  correct  average  test  of  the  entire 
quantity  of  milk.  The  accuracy  of  such  an  average 
figure  will  depend  on  the  uniformity  in  the  composition 
and  weights  of  the  ten  lots  of  milk.  When  there  is  no 
uniformity,  the  weights  of  the  different  lots  of  milk  as 
well  as  their  tests  must  be  considered.  The  following 
example  illustrates  the  difference  between  the  arithmet- 
ical average  of  a  number  of  single  tests  and  the  true 
average  test  of  the  various  lots. 

Methods  of  calculating  average  percentages. 


1.  Milk  varying  in  weights  and  tests. 

II.  Milk  of  uniform  weights  and  tests. 

Lot. 

o 

Lot. 

bt-- 

11 

Is 

I 

it.s. 

120 

570 

360 

5.5 

82 

per  ct. 

3.5 
5.0 
5.2 
3  0 
4.0 

fts. 

4.2 

28.5 

18  7 

1.6 

3.2 

I 

fts. 

250 
225 
240 

'238 
284 

per  ct. 
4.2 

IS 

4  1 

4.4 

lbs. 
10.5 

11 

II 

90 

III 

Ill 

10  3 

IV 

IV         

9.7 

V 

V 

10.3 

Total 

Total 

1187 
237 

4.14 
4.731 

56.2 
11.24 

1187 
237 

49.8 

Average.... 

Trueaver'ge 

test 

Average 

True  average 
test       

4.20 
4.222 

10.0 

156.2X100 
1187 


=4.73. 


2  49.8X100 
1187      '' 


:4.22. 


Composite  Samples  of  Milk.  161 

195.  The  figures  given  in  the  table  show  that  when 
the  different  lots  of  milk  vary  in  test  and  weight,  as  in 
the  first  case,  the  correct  average  test  of  the  1187  lbs.  of 
milk  is  not  found  by  dividing  the  sum  of  these  tests  by 
five,  which  would  give  4.14  per  cent. ;  but  the  percentage 
which  56.2  (the  total  amount  of  fat  in  the  mixed  milk) 
is  of  1187  (the  total  amount  of  milk),  is  4.73,  and  this 
is  the  correct  average  test  of  the  mixed  milk  made  up 
of  the  five  different  lots. 

In  the  second  case,  the  variations  in  both,  the  weights 
of  the  different  lots  of  milk  and  their  tests,  are  compara- 
tively small,  and  both  methods  of  calculation  give  there- 
fore practically  the  same  average  test;  but  also  in  this 
case,  the  correct  average  test  is  found  by  dividing  the 
total  amount  of  fat  by  the  total  quantity  of  milk,  making 
4.22  per  cent.,  instead  of  4.20  per  cent.,  which  is  the 
arithmetical  mean  of  the  five  tests.  The  quantities  of 
milk  in  the  various  lots  do  not  enter  into  the  calculation 
of  the  latter.  ^ 

196.  The  second  example  represents  more  nearly  than 
the  first  one  the  actual  conditions  met  with  at  creameries 
and  cheese  factories.  As  a  rule  the  mixed  milk  from  a 
herd  of  cows  does  not  vary  more  in  total  weight  or  tests, 
within  a  short  period  of  time  like  one  to  two  weeks,  than 
the  figures  given  in  this  example.  On  account  of  this 
fact,  samples  taken,  for  instance,  with  a  small  dipper  may 
give  perfectly  satisfactory  results  to  all  parties  concerned. 
If  the  different  lots  of  milk  varied  in  weight  and  test  from 


1  In  the  experiment  given  on  p.  137,  tlie  arithmetical  mean  of  the  tests 
given  is  5.15  per  cent.,  while  the  true  average  fat  content  of  the  milk  is  4.85 
per  cent. 

11 


162  Testing  Milk  and  Its  Products. 

day  to  day,  as  shown  in  the  first  case,  it  would  be  neces- 
sary to  use  a  *'  milk  thief"  or  one  of  the  sampling  tubes 
for  taking  the  composite  samples;  the  size  of  each  of  the 
samples  taken  would  then  represent  an  exact  aliquot  por- 
tion of  the  various  lots  of  milk  (180). 

197.  A  patron's  dilemma.  The  following  incident  will  further 
explain  the  difficulties  met  with  in  calculating  the  average  tests 
of  different  lots  of  milk. 

The  weekly  comporfite  sample  of  the  milk  supplied  by  a 
creamery  patron  from  his  herd  of  21  cows  tested  4.0  percent,  fat. 
One  day  the  farmer  brought  to  the  creamery  a  sample  of  the 
morning's  milk  from  each  of  his  cows,  and  had  them  tested ;  after 
adding  the  tests  together  and  dividing  the  sum  by  21, he  obtained 
an  average  figure  of  5.1  percent,  of  fat.  From  this  he  concluded 
that  the  average  test  of  the  milk  from  his  cows  ought  to  be  5.1, 
instead  of  4.0,  and  naturally  asked  for  an  explanation. 

198.  The  first  thing  done  was  to  show  him  that  while  5.1  was 
the  correct  average  of  the  figures  representing  the  tests  of  his 
twenty-one  cows,  it  was  not  a  correct  average  test  of  the  mixed 
milk  of  all  his  cows,  as  he  had  not  considered,  in  calculating 
this  average,  the  quantities  of  milk  yielded  by  each  cow;  the 
following  illustration  was  used: 

Cow  No.  1,  yield  25  lbs.  of  milk,  test  3.6  per  cent. =0.9  lbs.  of  butter  fat. 
Cow  No.  2,  yield   6  lbs.  of  milk,  test  5.0  per  cent. =0.3  ft)S  of  butter  fat. 

Total 31  lbs.  2-)8^  1  2  lbs. 

4.3  per  cent. 

The  two  cows  gave  31  fts.  of  milk  containing  1.2  lbs.  of  fat; 
the  test  of  the  mixed  milk  would  therefore  not  be  4.3  per  cent. 

(^:^j^),  but  ^-^^^=3.87  per  cent.      If  the  fat  in  the  mixed 

milk  was  calculated  by  the  average  figure  4.3  per  cent.,  1.33  lbs. 
of  fat  would  be  obtained,  i.  e.,  0.13  lbs.  more  than  the  cows 
produced. 

In  order  to  further  demonstrate  the  actual  composition  of 
the  mixed  milk  of  the  twenty-one  cows,  the  milk  of  each  cow 
was  weighed  and  tested  at  each  of  the  two  milkings  of  one  day. 
The  weights  and  tests  showed  that  the  cows  produced  the  fol- 
lowing total  number  of  pounds  of  milk  and  of  fat: 


Composite  Samples  of  Milk.  i63 

Morning  milking,  113.3  lbs.  of  milk,  containing  5.17  lbs  of  fat 
Night  milking,  130.9  fts.  of  milk,  containing  4.98  lbs.  of  fat. 


The  morning  milk  therefore  contained 


5.17  X  100 
113.3 


4.56  per 


cent,  of  fat,  and  the  night  milk 


X  100 


130. 


=3.80  percent,  of  fat. 


The  sum  of  the  morning  and  night  milkings  gave:  milk 
244.2  lbs.,  fat  10.15  lbs.  The  mixed  morning  and  night  milk' 
therefore,  contained  '^:^^=4. 1  per  cent,  of  fat.  This  is  the 
true  average  test  of  the  morning  and  night  milkings  of  these 
twenty-one  cows,  as  found  by  weighing  and  testing  separately 
the  milk  of  each  cow  at  both  milkings. 

199.  The  total  milk  was  strained  into  a  large  can  at  the  farm, 
both  in  the  morning  and  in  the  evening.  A  sample  of  the 
mixed  milk  was  in  each  case  taken  with  a  long-handled  dipper 
as  soon  as  the  milkings  were  finished.  When  i  he  cans  of  milk 
were  delivered  at  the  creamery,  a  sample  of  each  was  taken 
with  a  Scovell  sampling  tube.  The  tests  of  these  four  samples 
are  given  below,  together  with  the  results  from  the  individual 
tests: 


Sample  taken  at  the  farm,  with 
dipper 

Sample  taken  at  creamery  with  Sco- 
vell tube 

Calculated  from  weights  and  tests  of 
milk  from  each  cow 


Morning  Milk 


4.4perct. 
4.5     " 
4.5     " 


Night  Milk. 


3.8  per  ct. 

3.7  " 

3.8  " 


The  figures  given  show  that  practically  uniform  tests  were 
obtained  by  the  different  methods  of  sampling. 

The  sum  of  the  weights  of  the  milk  from  the  different  cows 
was  as  follows: 


Total  milk  produced 

Milk  in  samples 

Milk  for  family  use 

Milk  taken  to  creamery 


Morning  Milk. 


113.3  lbs. 

12.3  lbs. 

2.5  lbs. 


}.5  lbs. 


Night  Milk. 


130.9  lbs. 
8.9  lbs. 


122.0  lbs. 


Daily  Milk. 


244.2  lbs. 

21.2  lbs. 

2.5  lbs. 


220.5  lbs. 


164  Testing  Milk  and  Its  Products. 

It  has  already  been  shown  from  the  weights  and  tests  of  each 
cow's  milk  that  the  herd  milk  contained  4.1  percent,  of  fat. 
Multiplying  the  total  milk  delivered  at  the  creamery,  220.5  lbs., 
by  .041  gives  9.04  lbs.  of  fat.  The  morning  and  nightmilkings, 
which  were  weighed  and  tested  separately,  contained  the  fol- 
lowing quantities  of  butter  fat: 

Morning  Milk 98.5  lbs. X. 04.5 =4. 43  lbs.  of  butterfat 

Night  Milk 122.0  U.S.  X. 038=4. 63  lbs.  of  butter  fat 

Total 220.5  fljs.  9.06  fts. 

By  weighing,  sampling  and  testing  separately  the  morning 
and  night  milkings  of  twenty-one  cows,  deducting  the  weight 
of  milk  in  the  samples  and  what  was  taken  out  for  family  use, 
it  was  found  that  9.04  lbs.  of  butter  fat  was  sent  to  the  creamery. 
The  weights  and  tests  of  this  same  milk  when  delivered  at  the 
creamery,  gave  9.06  fts.  of  butter  fat. 

200.  This  example  furnishes  an  excellent  illustration  of  the 
accuracy  of  the  Babcock  test  and  of  the  closeness  of  results  which 
may  be  obtained  at  creameries  when  proper  care  is  taken  in 
weighing,  sampling  and  testing  the  milk.  Similar  demonstra- 
tions may  be  made  by  any  factory  operator,  and  with  equally 
satisfactory  results,  provided  the  work  is  carefully  done. 


CHAPTEE  XI. 
CREAM  TESriNQ  AT  CREAPIERIES. 

201.  The  cream  delivered  at  gathered- cream  factories 
is  now  in  many  localities  tested  by  the  Babcock  test,  and 
this  has  been  adopted  as  a  basis  of  paying  for  the  cream 
in  the  same  manner  as  milk  is  paid  for  at  separator 
creameries.  It  has  been  found  to  be  more  satisfactory  to 
both  cream  buyer  and  seller,  than  either  the  oil- test  churn 
or  the  space  (or  gauge)  systems  which  have  been  used 
for  this  purpose  in  the  past. 

The  details  of  the  application  of  the  Babcock  test  to 
the  practical  work  at  cream-gathering  creameries  have 
been  carefully  investigated  by  Winton  and  Ogden  in 
Connecticut,^  Bartlett  in  Maine,'  and  Lindsey  in  Massa- 
chusetts,^ and  we  also  owe  to  the  labors  of  these  chemists 
much  information  concerning  the  present  workings  of 
other  systems  of  paying  for  the  cream  delivered  at 
creameries. 

202.  The  space  system.  Numerous  tests  have  shown 
that  one  space  or  gauge  of  cream  does  not  contain  a  defi- 
nite, uniform  amount  of  fat.  In  over  100  comparisons 
made  by  Winton  it  was  found  that  one  space  of  cream  * 

1  Conn,  experiment  station  (New  Haven),  bull.  No.  108  and  119  ;  report 
1894,  pp.  214-24 <. 

2  Maine  experiment  station,  bull.  3  and  4  (S.  S.). 

3  Hatch  experiment  station,  report  1894,  pp.  92-103  ;  1895,  pp.  67-70. 

4  The  space  is  the  volume  of  a  cylinder,  8%  inches  in  diameter  and  ^|  of 
an  inch  high.  The  number  of  spaces  in  each  can  of  milk  is  read  off  before 
skimming  by  means  of  a  scale  marked  on  a  strip  of  glass  in  the  side  of  the 
can  (Conn.  exp.  sta.,  bull.  No  119). 


166  Testing  Milk  and  Its  Products. 

contained  from  .072  to  .170  lbs.  of  butter  fat,  or  on  the 
average  .IS^flb.,  and  the  number  of  spaces  required  to 
make  one  pound  of  butter  varied  from  5.01  to  11.72.  It 
is  also  claimed  that  in  the  winter  season  when  the  cream 
is  gathered  at  long  intervals,  like  once  a  week,  it  is  neces- 
sary for  the  buyer  to  accept  the  seller's  statement  of  the 
record  of  the  number  of  cream  spaces  which  he  furnishes, 


Fig.  56.    The  oil-test  cburn. 

since  the  cream  cannot  be  left  in  the  creaming  cans  for 
so  long  a  time.  These  objections  to  the  space  system 
apply  only  to  the  method  of  paying  for  the  cream,  and 
not  to  the  manner  in  which  the  cream  is  obtained. 

203.  The  oil-test  churn.  As  stated  in  the  introduction, 
the  oil-test  churn  (fig.  56)  has  been  used  quite  extensively 
among  gathered-cream  factories j  this  system  is  based  on 


Cream  Testing  at  Creameries. 


167 


-^^^ 


liiiWillt 


'iMMMMMMMmi 


the  number  of  creamery  inches  of  cream  which  the 
various  patrons  deliver  to  the  factory;  one  inch  of  cream 
contains  113  cubic  inches.^  The  driver  pours  the  patron's 
cream  into  his  12-inch  gathering  pail,  measures  it  with 
his  rule  and  records  the  depth  of  the  cream  in  the  can, 
in  inches  and  tenths  of  an  inch.  The  cream  is  then  stirred 
thoroughly  with  a  ladle  or  a  stout  dipper,  and  a  sample 
is  taken  by  filling  a  test  tube  from  the  sample  case,  to  the 
graduation  mark  by  means  of  a  small  conical  dipper  pro- 
vided with  a  lip.  A  driver's  case  contains  either  two  or 
three  ^ 'cards,"  holding  fifteen  test  tubes  each  (see  fig.  57). 
The  tubes  as  filled  are 
placed  in  the  case  and 
the  corresponding  num- 
ber is  in  each  instance 
recorded  in  front  of  the 
patron's  name  together 
with  the  number  of 
inches  of  cream  fur- 
nished by  him. 

On  the  arrival  at  the 
creamery  the  tin  cards 
holding  the  tubes  are  placed  in  a  vessel  filled  with 
water  of  the  temperature  wanted  for  churning  (say,  60° 
in  summer  and  65°  to  70°  in  winter).  When  ready  for 
churning  they  are  placed  in  the  oil- test  churn,  the  cover 
of  the  churn  put  on,  and  the  samples  of  cream  churned 
to  butter.  On  the  completion  of  the  churning,  the 
cards    are   transferred    to    water   of    175-190°    Fahr., 

1  I.  e.,  a  layer  of  cream  one  inch  deep  in  a" ;i2-inch  pail;- two  inches  in 
an  8-inch  pail  contains  10  ).531  cubic  inches,  two  inches  in  an  8%-inch  pail 
110.18  cubic  inches,  and^two.inches.in  an  8>^-inch.pail  113.49  cubic  inche.s. 


Fig.  57.    Cream-gatherer's 
sample  case. 


168  Testing  Milk  and  Its  Products. 

wliere  they  are  left  for  at  least  ten  minutes  to  melt  the 
butter  and  ^'cook  the  butter  milk  into  a  curd."  The 
oil  will  now  be  seen  mixed  all  through  the  mass.  The 
test  tubes  are  then  warmed  to  churning  temperature 
and  churned  again,  by  which  process  the  curd  is  broken 
into  fine  particles,  which,  when  the  butter  is  re- melted, 
will  settle  to  the  bottom.  The  butter  is  melted  after 
the  second  churning  by  placing  the  tubes  in  water  at 
150-175°  F.,  allowing  them  to  remain  therein  for  at 
least  twenty  minutes.  Some  samples  must  be  churned 
three  or  four  times  before  a  good  separation  of  oil  is 
obtained.  A  clear  separation  of  oil  is  often  facilitated 
by  adding  a  little  sulfuric  acid  to  the  tubes. 

The  length  of  the  column  of  liquid  butter  fat  is  de- 
termined by  means  of  a  special  rule  for  measuring  the 
butter  oil;  this  rule  shows  the  number  of  pounds  and 
tenths  of  a  pound  of  butter  which  an  inch  of  cream  will 
make;  the  first  tenth  of  a  pound  on  the  rule  is  divided 
into  five  equal  parts,  so  that  measurements  may  be  made 
to  two- hundredths  of  a  pound.  The  melted  fat  is  meas- 
ured with  the  rule,  by  raising  the  tin  card  holding  the 
bottles,  to  about  the  height  of  the  eye;  the  reading  is 
recorded  on  the  driver's  tablet  under  Test  per  inch,  oppo- 
site the  number  of  the  particular  patron.  The  test  per 
inch  multiplied  by  the  inches  and  tenths  of  an  inch  of 
cream  supplied  will  give  the  butter  yield  in  pounds, 
with  which  the  patron  will  be  credited  on  the  books  of 
the  creamery. 

204.  The  objection  to  this  system  of  ascertaining  the 
quality  of  cream  delivered  by  different  patrons  lies  in 
the  fact  that  it  determines  the  churnahle  fat,  and  not  the 


Cream  Testing  at  Creameries.  169 

total  fat  of  the  cream;  the  amount  of  the  former  obtained 
depends  on  many  conditions  beyond  the  control  of  the 
patron,  viz.,  the  consistency,  acidity  and  temperature  of 
the  cream,  the  size  of  the  churn  or  churning  vessel,  etc. 
The  same  reasons  which  caused  the  churn  to  be  replaced 
by  methods  of  determining  the  total  fat  of  the  milk,  in 
the  testing  of  cows  among  dairymen  and  breeders,  have 
gradually  brought  about  the  abandonment  of  the  oil  test 
in  creameries  and  the  adoption  of  the  Babcock  test  in 
its  place. 

205.  The  Babcock  test  for  cream.  Both  the  space 
system  and  the  oil-test  churn  used  for  estimating  the 
quality  of  cream  at  creameries  have  now  largely  been 
replaced  by  the  Babcock  test  in  the  more  progressive 
creameries  in  this  country,  and  composite  samples  of 
cream  are  collected  and  tested  in  a  similar  manner  as 
is  done  with  milk  at  separator  creameries  and  cheese 
factories. 

A  very  satisfactory  method  of  arrangements  for  work- 
ing the  Babcock  test,  in  use  in  many  eastern  creameries, 
is  described  by  Winton  and  Ogden  in  the  Connectic  ut 
report  previously  referred  to.  The  cream  gatherer  who 
collects  the  cream  in  large  cream  cans  is  supplied  with 
a  spring  balance  (1,  see  fig.  58),  pail  for  sampling  and 
weighing  the  cream  (2),  sampling  tube  (3),  and  collect- 
ing bottles  (5).  At  each  patron's  farm  he  takes  from 
his  wagon  the  sampling  pail  and  tube,  the  scales,  and  one 
small  collecting  bottle.  He  should  find  in  the  dairy  of 
the  patron  the  cans  of  perfectly  sweet  cream,  kept  at  a 
temperature  of  40°  to  50°  F.,  and  protected  from  dirt  and 
bad  odors.  Either  sour  or  frozen  cream  must  be  rejected. 


170 


Testing  Milk  and  Its  Products. 


Fig.  58.    Outfit  for  cream  testing  by  the  Babcock  test  at  gathered- 
cream  factories. 

The  patron's  number  should  be  painted  in  some  conspic- 
uous place  near  the  cream  cans  in  his  dairy  house.  The 
gatherer  hangs  the  scale  on  a  hook  near  the  cream  to  be 
collected;  the  scale  should  be  so  made  that  the  hand  of 
the  dial  will  stand  at  zero  when  the  empty 'pail  is  hung 


Testing  Cream  at  Creameries.  171 

on  it.     The  cream  is  then  poured  at  least  twice  from  one 
can  to  another  in  order  to  mix  it  thoroughly.  ^ 

206.  When  properly  mixed,  the  cream  is  poured  into 
the  weighing  pail  and  is  weighed  and  sampled.  The 
authors  give  the  following  description  of  the  cream  sam- 
pling tube  used,  and  directions  for  sampling  and  weigh- 
ing the  cream. 

'^Sampling  Tube. — This  tube,  devised  by  Mr.  Ogden,  is  of 
stout  brass,  about  ^^  of  an  inch  thick,  and  a  few  inches  louger 
than  the  weighing  pail  which  is  used  with  it.  On  the  upper 
end,  a  small  brass  stop-cock  of  the  same  bore  is  fastened.  It 
should  be  nickel  plated  inside  and  out,  to  keep  the  metal 
smooth  and  free  from  corrosion.  These  tubes  may  be  obtained 
from  less  than  j\  to  over  \  inch  bore.  The  greater  the  diameter 
of  the  weighing  pail,  the  wider  should  be  the  bore  of  the  tube. 
For  use  with  pails  8  inches  in  diameter,  a  ^^  inch  bore  sampling 
tube  will  serve  the  purpose,  but  when  the  pail  has  a  diameter 
of  9  or  more  inches,  a  tube  with  a  bore  of  \  inch  or  more  should 
be  used.  It  must  be  borne  in  mind  that  doubling  the  diameter 
of  the  pail,  or  of  the  sampling  tube,  increases  its  capacity 
fourfold. 

"The  tube  when  not  in  use  should  be  kept  in  an  upright 
position  to  permit  draining. 

^^  Sampling  and  Weighing.— Ltower  the  sampling  tube,  cock 
end  up,  with  the  cock  open,  to  the  bottom  of  the  weighing  pail 
which  holds  the  mixed  cream.  When  it  is  filled  raise  it  out  of 
the  liquid  and  allow  it  to  drain  for  a  few  seconds.  By  this 
means  the  tube  is  rinsed  with  the  cream  to  be  sampled  and  any 

1  The  neceBstty  of  care  in  mixing  the  cream  is  shown  by  the  following 
illustration  given  by  the  authors  referred  to. 

Per  cent  of  fat  in  cream  which  stood  for  2U  hours. 

Sample  drawn 
Surface.  Bottom,  with  sampling  tube. 

Not  mixed 2S.00  5.00  19.25 

Poured  once 23.75  22.00  22.50 

Poured  twice 22.25 


172  Testing  Milk  and  Its  Froducis. 

traces  of  cream  adhering  to  the  tube  from  previous  use  are 
removed.  With  the  cock  still  open,  slowly  lower  the  sampling 
tube  to  the  bottom  of  the  cream  pail.  After  allowing  a  moment 
for  the  cream  to  rise  in  the  tube  to  the  same  height  as  in  the 
pail,  close  the  cock  and  raise  the  sampler  carefully  out  of  the 
cream.  As  long  as  the  cock  is  closed,  the  cream  in  the  tube 
will  not  flow  out,  unless  the  tube  is  strongly  jarred.  Allow  the 
cream  adhering  to  the  outside  of  the  tube  to  drain  off  for  a  few 
seconds,  then  put  the  lower  end  into  the  1  to  1.^  oz.  wide-mouth 
glass  collecting  bottle  which  bears  the  patron's  number  on  its 
cork,  and  open  the  cork.  The  cream  will  then  flow  out  of  the 
sampler  into  the  bottle,  which  is  afterwards  securely  corked  and 
put  into  the  cream  gatherer's  case.  Immediately  weigh  the 
cream  in  the  cream  pail  to  the  quarter  or  half  pound,  as  may 
be  judged  expedient,  and  record  the  weight. 

"If  the  patron  has  more  than  one  pailful,  rep^at  with  each 
pailful  the  operation  of  sampling  and  weighing,  putting  all  the 
samples  in  one  and  the  same  bottle.  Weigh  all  cream  collected 
in  one  and  the  same  sampling  pail  and  draw  a  sample  from, 
each  separate  portion  iveighed.^^ 

207.  After  sampling  and  weighing  each  patron' s  cream 
it  is  poured  into  the  driver's  large  can,  and  the  sample 
bottles  are  carried  in  a  case  to  the  creamery  where  the 
contents  of  each  bottle  is  poured  into  the  composite 
sample  jar  of  the  particular  patron.  The  samples  of 
cream  in  the  small  bottles,  besides  furnishing  the  means 
of  testing  the  richness  of  the  cream,  give  the  creamery 
owner  or  manager  an  opportunity  to  inspect  the  flavor 
of  each  lot  of  cream,  and  the  condition  in  which  it  has 
been  kept  by  the  various  patrons. '  Potassium  bi-chro- 
mate  is  placed  in  the  composite  sample  jars,  and  these 
are  cared  for  and  tested  in  the  same  manner  as  composite 
samples  of  milk  (192). 

208.  The  collecting  bottles  should  be  cleared  with 
cold,  and  after vvards  with  hot  water,  as  soon  as  they  are 


Testing  Oream  at  Creameries.  173 

emptied,  and  before  a  film  of  cream  dries  on  them. 
When  washed  and  dried,  these  bottles  are  placed  in  the 
cases,  ready  for  the  next  collecting  trip.  There  can 
be  no  confusion  of  bottles  since  the  corks  and  not  the 
bottles  are  marked  with  the  numbers  of  the  respective 
patrons. 

209.  When  this  system  of  testing  composite  sam- 
ples is  adopted,  the  patrons  are  paid  for  the  number 
of  pounds  of  butter  fat  contained  in  their  cream,  in  ex- 
actly the  same  way  as  milk  is  paid  for  at  separator 
creameries.  It  makes  no  difference  how  thick  or  how 
thin  the  cream  may  be,  or  how  much  skim  milk  is  left 
in  the  cream  when  brought  to  the  factory.  Eighty 
pounds  of  cream  containing  15  per  cent,  of  fat  is  worth 
no  more  or  less  than  48  pounds  of  cream  testing  25  per 
cent.;  in  either  case  12  pounds  of  pure  butter  fat  is 
delivered.  This  will  make  the  same  amount  of  butter 
in  either  case,  viz.,  toward  14  lbs.,  and  both  patrons 
should  therefore  receive  the  same  amount  of  money. 

There  is  a  small  difference  in  the  value  of  the  two  lots 
of  cream  to  the  creamery  owner  or  the  butter  maker,  in 
favor  of  the  richer  cream,  both  because  its  smaller  bulk 
makes  the  transportation  and  handling  expenses  lighter, 
and  because  slightly  less  butter  fat  will  be  lost  in  the 
butter  milk,  a  smaller  quantity  of  this  being  obtained 
from  the  richer  cream.  But  it  is  doubtful  if  the  dif- 
ferences thus  occurring  are  of  sufficient  importance  to 
be  noticed  under  ordinary  creamery  conditions;  the 
example  selected  presents  an  extreme  case  of  variation 
in  the  fat  content  of  cream.  A  trial  of  this  system  at 
five  Connecticut  creameries,  supplied  mostly  with  Gooley 


174  Testing  Milk  and  Its  Products. 

cream,  by  over  175  patrons,  showed  that  the  average 
composition  of  the  cream  from  the  different  patrons 
varied  only  from  16.9  to  19.8  per  cent.  fat.  The  cream 
of  some  patrons  on  certain  days  contained  only  9.5  per 
cent,  of  fat,  and  other  patrons  at  times  had  as  high  a 
test  as  30  per  cent.,  but  these  great  differences  largely 
disappeared  when  the  average  quality  of  the  cream 
delivered  during  a  period  of  time,  like  a  month  or  more, 
was  considered. 

210.  Smaller  differences  in  the  composition  of  cream 
will,  however,  always  occur,  even  if  the  same  system  of 
setting  the  milk,  like  the  cold  deep-setting  process,  is 
used  and  the  water  is  kept  at  the  same  temperature  at 
all  times.  This  is  due  to  differences  in  the  composition 
of  the  milk  and  its  creaming  quality;  whether  largely 
from  fresh  cows  or  from  late  milkers;  whether  kept 
standing  for  a  time  before  being  set  or  submerged  in 
the  creamer  immediately  after  milking  and  straining; 
diameter  of  creaming  cans,  etc.  Bartlett  states^  that  the 
percentage  of  fat  in  the  cream  from  the  same  cows  may 
be  increased  ten  per  cent,  or  more  by  keeping  the  water 
at  70°  instead  of  at  40°  F.  The  higher  temperature  will 
give  the  richer  cream,  but  the  separation  will  not  be  so 
complete,  since  a  richer  skim  milk  is  obtained  from  the 
milk  set  at  this  temperature.  Separator  cream  is  not 
materially  influenced  by  the  conditions  mentioned,  as 
the  separator  can  be  regulated  to  deliver  cream  of  nearly 
uniform  richness  from  all  kinds  of  sweet  milk. 

211.  At  creameries  where  both  milk  and  cream  are  de- 
livered, somewhat  of  an  injustice  is  done  to  patrons  de- 

1  Maine  experiment  station,  bulletin  INo.  3  (S.  S.). 


Testing  Cream  at  Creameries.  175 

livering  cream,  by  paying  for  the  amounts  of  butter  fat 
furnished  by  the  different  patrons.  By  multiplying  the 
cream  fat  by  1.03  (or  by  1.044^),  the  value  of  his  pro- 
ducts to  the  creamery  is  taken  into  proper  account,  and 
justice  is  done  to  all  parties  concerned^  (238). 

iSee  Spillman.  Dairy  and  Creamery,  Chicago,  April  1,  1899. 

2  This  subject  is  discussed  in  detail  in  the  17th  annual  report  of  Wis. 
experiment  station,  pp.  v»0-92;  see  also  the  20th  report  of  this  Station  pp" 
130-31. 


CHAPTEE  XII. 
CALCULATION  OF  BUTTER  AND  CHEESE  YIELD. 

A. — Calculation  of  Yield  of  Butter. 

212.  Butter-fat  test  and  yield  of  butter.  The  Babcock 
test  shows  the  amount  of  pure  butter  fat  contained  in  a 
sample  of  milk  or  other  dair}^  products.  The  butter  ob- 
tained by  churning  cream  or  milk  contains,  in  addition 
to  pure  butter  fat,  a  certain  amount  of  water,  salt  and 
curd.  While  an  accurate  milk  test  gives  the  total  quan- 
tity of  butter  fat  found  in  the  sample  of  milk  or  cream 
tested,  the  churn  cannot  be  depended  upon  either  to 
leave  the  same  amount  of  butter  fat  in  the  butter  milk  or 
to  include  the  same  amount  of  water,  salt  and  curd  in  the 
butter  at  each  churning. 

If  a  quantity  of  milk,  say  3,000  lbs.,  be  thoroughly 
mixed  in  a  vat,  and  then  divided  into  half  a  dozen  equal 
portions,  a  Babcock  test  of  the  different  lots  will  show 
the  same  percentage  of  butter  fat  in  each  portion.  If,  on 
the  other  hand,  each  of  these  lots  be  skimmed,  and  the 
cream  ripened  in  different  vats  and  churned  separately, 
the  same  weight  of  butter  from  each  lot  of  500  lbs.  of 
milk  will  not  be  obtained,  even  by  the  most  expert  but- 
ter maker,  or  if  all  the  operations  of  skimming,  cream 
ripening,  churning,  salting  and  butter- working  were 
made  as  nearly  uniform  as  possible.      Careful  operators 


Calculation  of  Butter-  and  Cheese  Yield. 


m 


can  handle  the  milk  and  cream  so  that  very  nearly  the 
same  proportion  of  the  fat  contained  in  the  milk  is  re- 
covered in  the  butter  in  different  churnings,  but  since  the 
water  and  salt  in  butter  are  held  mechanically  and  are 
not  chemically  combined  with  it,  the  amounts  retained 
by  the  butter  are  quite  variable  in  different  churnings, 
especially  since  the  laws  governing  the  retention  of  water 
in  butter  are  but  imperfectly  understood. 

213.  Variations  in  the  composition  of  butter.  As  an 
illustration  of  the  variability  of  butter  in  its  composition, 
the  analyses  made  in  the  breed  tests  at  the  World's  Fair 
in  1893  may  here  be  cited;  the  butter  was  in  all  cases 
made  by  as  nearly  identical  methods  and  under  as  uni- 
form conditions  as  could  possibly  be  obtained  by  the 
skilled  operators  having  this  work  in  charge;  the  aver- 
age composition  of  350  samples  of  this  butter,  with  upper 
and  lower  limits,  was  as  shown  in  the  following  table: 

Composition  of  samples  of  butter,  WojWs  Fair,  1893. 


Average  of  350 
analyses 

Lower  and  upper 
limits 


Water. 


Per  cent. 

11.57 

8.63-15  CO 


Fat. 


Per  cent. 

81.70 
76  5:^-88.26 


Curd. 


Per  cent. 

.95 
.50-2.14 


Salt  and 
ash. 


Per  cent. 

2.78 
1.01-8.58 


Sum  of 

water,c'rd, 

salt  and 


Per  cent. 
15.30 


Analyses  of  fifty  samples  of  creamery  butter  taken  in 
1896,  from  the  tubs  ready  for  market  at  as  many  Wiscon- 
sin creameries,  showed  that  no  two  of  them  were  ex- 
actly alike  in  composition,  but  varied  within  the  limits 
given  below:  ^ 

1  Wisconsin  experiment  station,  bull.  56. 
12 


178  Testing  Milk  and  Its  Products. 

Summary  of  analyses  of  Wisconsin  creamery  butter. 


Highest.. 
Lowest... 
Average. 


Water. 


Per  cent. 

17.03 
9.18 
12.77 


Fat. 


Per  cent. 

87.50 
77.07 
83.08 


Curd. 


Per  cent. 

2.45 
.86 

1.28 


Salt  and 


Per  cent. 

4  73 
1.30 

2.87 


Sum  of 

water,  curd, 

salt  and 

ash. 


Per  cent 

22. 95 
12.50 
16.92 


The  preceding  analyses  show  the  composition  of  butter 
made  at  one  place  where  every  possible  effort  was  taken 
to  produce  a  uniform  product,  and  of  butter  made  at 
fifty  different  creameries,  where  there  was  more  or  less 
variation  in  the  different  operations  of  manufacture  and 
in  the  appliances  and  machinery  used.  The  majority  of 
the  samples  of  butter  analyzed,  in  either  case,  were  very 
near  the  average  composition  given,  but  since  there  are 
such  wide  variations  in  the  composition  of  the  butter 
made  by  the  uniform  methods  adopted  in  the  World's 
Fair  breed  tests,  butter  of  a  more  uniform  composition 
cannot  be  expected  from  the  thousands  of  different  cream- 
eries and  private  dairies  which  supply  the  general  market 
with  butter. 

The  analyses  of  the  fifty  samples  of  creamery  butter, 
given  above,  show  that  the  content  of  the  butter  fat 
varied  from  77  to  over  87.5  per  cent.,  and  according  to 
the  average  of  the  analyses,  83  pounds  of  butter  fat  was 
contained  in,  or  made,  100  lt)S.  of  butter.  There  was, 
therefore,  in  this  case  produced  20.5  per  cent,  more 
butter  than  there  was  butter  fat,  since 

83  :  100  :  :  100  :  xj  therefore 


100  X  100 

83 


120.5. 


Calculation  of  Butter-  and  Cheese  Yield.  179 

214.  **  Overrun "  of  churn  over  test.  The  yield  of 
butter  is  not,  however,  as  a  rule  compared  with  the 
amount  of  butter  fat  contained  in  the  butter,  but  with 
the  total  butter  fat  of  the  whole  milk  from  which  it  was 
made.  This  "iacrease  of  the  churn  over  the  test"  is 
what  is  generally  called  overrun  in  creameries. 

The  overrun  obtained  in  different  creameries,  or  even 
in  the  same  creameries  at  different  times,  will  be  found 
to  vary  considerably.  When  the  milk  is  accurately 
tested  and  the  butter  well  worked,  this  overrun  will  vary 
from  10  to  16  per  cent.  ;  that  is,  if  a  quantity  of  milk 
contains  exactly  100  lbs.  of  butter  fat,  as  found  by  the 
Babcock  test  or  any  other  accurate  method  of  milk  test- 
ing, from  110  to  116  lbs.  of  butter  ready  for  market  may 
be  made  from  it. 

215.  Factors  influencing  the  overrun.  Even  under  the 
very  best  of  care  and  attention  to  details,  variations  will 
occur  in  the  speed  of  the  separator,  in  the  conduct  of  the 
ripening  and  churning  processes,  and  in  the  condition  of 
the  butter  when  the  churn  is  stopped;  hence  absolutely 
uniform  losses  of  fat  in  skim  milk  and  butter  milk,  or 
the  same  water-  and  salt  contents  of  the  butter,  cannot 
be  expected. 

The  overrun  is  influenced  by  two  factors:  the  losses  of 
butter  fat  sustained  in  separating  the  milk  and  churning 
the  cream,  and  the  gain  due  to  the  admixture  of  water, 
salt,  etc.,  in  the  manufacture  of  butter.  Considering 
first  the  losses  of  fat  in  skim  milk  and  butter  milk,  the 
separator  will  usually,  when  run  at  normal  speed  and 
capacity,  leave  the  same  per  cent,  of  fat  in  skim  milk, 
whether  rich  or  poor  milk  is  skimmed.     An  exception 


180  Testing  Milk  and  Its  Products. 

to  this  may  be  found  in  separating  rich  milk  having 
large  fat  globules  or  milk  from  fresh  milkers,  in  either 
of  which  cases  the  large  size  of  the  fat  globules  occasions 
a  more  complete  separation  of  fat  by  the  centrifugal 
force.  But  generally  speaking,  the  statement  holds  good 
that  the  total  loss  of  fat  in  separator  skim  milk  is  a  factor 
of  the  quantity  of  milk  run  through  the  separator,  rather 
than  of  its  quality.  It  follows  from  this,  however,  that 
the  relative  losses  of  fat  in  skim  milk  will  vary  to  some 
extent  according  to  the  quality  of  the  milk  separated. 
Selecting  two  extremes  in  the  quality  of  milk,  2.5  and 
6.0  per  cent,  of  fat,  there  will  be  found,  say  .2  per  cent, 
of  fat  in  the  skim  milk  from  either  lot,  provided  the  sep- 
arator is  not  unduly  crowded,  and  the  separation  is  con- 
ducted under  normal  conditions  in  each  case.  But  .2 
per  cent,  fat  makes  8  per  cent,  of  the  total  fat  in  the  poor 

2X It  0 

milk  (^^^ — =8),  and  only  3  per  cent,  of  that  in  the  rich 
milk.  It  takes  4000  lbs.  of  the  2.5  per  cent,  milk  to 
furnish  100  lbs.  of  fat,  and  only  1666  tbs.  of  the  6  per 
cent,  milk;  in  skimming  the  poor  milk,  a  loss  of  .2  per 
cent,  of  fat  is  sustained  in  the  skim  milk  from  4000  fts. 
of  milk,  while  in  the  rich  milk  a  similar  loss  is  sustained 
in  the  skim  milk  from  only  1666  lbs.  of  milk. 

The  example  gives  an  extreme  case,  and  one  not  likely 
to  be  met  with  in  practice.  Therangein  the  richness  of 
the  milk  delivered  by  different  patrons  at  the  factory  is 
usually  within  one-half  or  one  per  cent  of  fat.  In  such 
cases  the  proportion  of  fat  lost  in  skimming  does  not  vary 
much,  e.  g.,  in  case  of  milk  containing  3.5  and  4.0  per 
cent,  of  fat,  and  variations  in  the  overrun  occurring  when 
the  proper  care  in  skimming,  ripening  and  churning  is 


Calculation  of  Butter-  and  Cheese  Yield. 


181 


taken,  are  due,  therefore,  primarily  to  differences  in  the 
water-  and  salt  contents  of  the  butter  made  (205). 

216.  The  losses  from  very  poor,  very  rich  and  average 
milk,  as  received  at  creameries  and  cheese  factories,  can 
be  traced  from  the  following  statement;  this. gives  the 
quantities  of  fat  lost  in  handling  milk  of  four  grades, 
viz:  2.5,  3.5,  4.0  and  6.0  per  cent.,  in  case  of  each  grade 
calculated  to  a  standard  of  100  lbs.  of  fat  in  the  milk. 

To  supply  100  lt)S.  of  fat  would  require  the  following 
amounts  of  the  different  grades  of  milk : 
4000  tt)s.  of  milk  testing  2.5  per  cent,  will  contain  100  lbs.  of  fat. 
2857         "       "  "        3.5       "  "  "        100         *'      " 

2500         "       "  "        4.0       "  "  "        100         "      " 

1666         "       "  "        6.0       "  "  "        100         "      " 

Assuming  that  the  skim  milk  contains  .2  per  cent,  of 
fat  and  makes  up  85  per  cent,  of  the  whole  milk,  that  the 
butter  milk  test  .3  per  cent.,  and  forms  10  per  cent,  of 
the  whole  milk,  the  butter- fat  record  of  the  quantities  of 
different  grades  of  milk  containing  100  lbs.  of  fat  will 
appear  as  follows: 

Fat  available  for  butter  in  different  grades  of  milk. 


Grade  of  milk. 

Whole 
milk. 

Skim  milk. 

Butter 
milk. 

Total 
loss. 

Fat 
aval  la 
ble  for- 
butter. 

2.5  per  cent  

4000  ftj. 
2.5  per  ct. 

3400  ftj. 
.2  perct. 

400  ft). 
.3  perct. 

ft.s. 
80 

5.8 

5.0 

3.3 

Percent. 

Fat   .. 

100  ft). 

2857   ft.. 
3.5perct. 

6.8  ft). 

2429  ft.. 
.2  perct. 

1.2  ft). 

286  ft>. 
.3  per  ct. 

92.0 

3.5  per  cent 

Fat ;..  . 

100  ft.. 

2500  ft). 
4  per  ct. 

4.9  ftj. 

2125  ft). 
.2  perct. 

.9  ft). 

250  lb. 
.3  per  ct. 

94.2 

4.0  per  cent 

Fat ^ 

6.0  per  cent 

100  ft). 

1666;^^  ftj. 
6  per  ct. 

4.3  ft>. 

1417  ft). 
.2per  ct. 

.7  ft) 

167  ft.. 
.3  per  ct. 

93.0 

Fat 

100  ft.. 

2.8  ft). 

.5  ftj. 

96.7 

182  Testing  Milk  and  Its  Products. 

The  table  shows  that  with  2.5  per  cent. -milk,  there  is 
a  loss  of  6.8  lbs.  of  fat  in  the  skim  milk  and  1.2  lbs.  of 
fat  in  the  butter  milk  for  every  100  lbs.  of  fat  in  the 
whole  milk,  or  a  total  loss  of  8.0  lbs.  from  these  sources. 
In  case  of  6  per  cent,  milk  these  losses  are  2.8  lbs.  and 
.5  lbs.  for  skim  milk  and  butter  milk,  respectively;  a 
total  loss  of  3.3  lbs.,  or  4.7  lbs.  less  than  the  losses  with 
the  very  poor  milk.  This  difference  in  the  losses  shrinks 
to  only  .8  pound  of  fat  in  case  of  3.5  and  4.0  per  ct.-milk, 
when  a  quantity  containing  100  lbs.  of  fat  is  handled  in 
both  cases. 

The  overrun  from  each  of  the  four  grades  of  milk  can 
be  calculated  for  butter  containing  a  certain  per  cent,  of 
fat.  Assuming  the  fat  content  of  butter  to  be  83  per  cent. , 
on  the  average  (213),  the  quantity  of  butter  obtained 
from  the  100  lbs.  of  fat,  or  rather  from  the  portion 
thereof  which  is  available  for  butter,  in  each  case  will  be 
as  follows: 

Butter  cont. 
Available/at.    8Spr.ct.fcU. 

100  lbs.  offat from 4000 R)s.  of  2.5  pr.  ct.  milk,  92.0  Ibs.^  110.8  lbs. 

100  "       "        "     2857      •'    3.5       "        "      94.2    *'    =  113.5  " 

100  "       "        "     2500      "    4.0      "        "      95.0    "   =  114.5  " 

100  "       "        "     1666       "    6.0       "        "      96.7    "    =  116.5  " 

The  overrun  in  each  case  will  be: 

For  2.5  per  cent.  milk=110.8-100=10.8  per  cent. 


3.5 

(i 

(( 

=  113.5-100=13.5 

4.0 

(( 

u 

=  114.5-100=14.5 

6.0 

(( 

(( 

=  116.5-100=16.5 

All  butter  makers  should  obtain  more  butter  from  a 
certain  quantity  of  milk  than  the  Babcock  test  shows  it 
to  contain  butter  fat,  but  it  is  impossible  to  know  exactly, 
except  by  "chemical  analysis,  how  much  butter  fat  is  lost 


Calculation  of  Butter-  and  Cheese  Jield.  183 

in  the  skim  milk  and  the  butter  milk,  and  how  much 
water,  salt  and  curd  the  butter  will  contain. 

217.  Calculation  of  overrun.  The  overrun  is  calculated 
by  subtracting  the  amount  of  butter  fat  contained  in  a 
certain  quantity  of  milk,  from  the  amount  of  butter  made 
from  it,  and  finding  the  per  cent,  which  this  difference  is 
of  the  amount  of  butter  fat  in  the  milk. 

Example:  8000  fts.  of  milk  is  received  at  the  creamery  on  a 
certain  day;  the  average  test  of  the  milk  is  3.8  per  cent. ;  340  lbs. 
of  butter  was  made  from  this  milk,  as  shown  by  the  weights  of 
the  packed  tubs.  By  a  simple  multiplication  we  fiud  that  the 
milk  contained  8000 X. 038=304  lbs.  of  butter  fat.  The  difference 
between  the  weight  of  butter  and  butter  fat  is,  therefore,  36  lbs. ; 
36is?6^^=11.8  per  cent,  of  the  quantity  of  butter  fat  in 
the  milk;  that  is,  the  overrun  for  the  day  considered  was  11.8 
per  cent. 

The  formula  for  the  overrun  is  as  follows: 

(b— f)   100 

b  and/ designating  the  quantities  of  butter  and  butter 
fat  respectively,  made  from  or  contained  in  a  certain 
quantity  of  milk.  In  the  preceding  example,  the  calcu- 
lation would  be  as  follows:  ^^^^5h^|^'^=11.8  per  cent. 

In  gathered- cream  factories  the  overrun  will  naturally 
come  higher  than  in  separator  creameries,  since  no  loss 
of  butter  fat  in  the  skim  milk  occurs  in  the  former.  The 
overrun  based  on  the  amount  of  fat  in  the  cream  will  not 
under  average  creamery  conditions  be  likely  to  vary 
much  from  18  per  cent. 

218.  Conversion  factor  for  butter  fat.  A  committee  of 
the  Association  of  American  Agricultural  Colleges  and 
Experiment  Stations  at  the  ninth  annual  convention  of 


184  Testing  Milk  and  Its  Products. 

the  Association  reported  that  '^  in  the  ninety- day  Colum- 
bian Dairy  Test,  96.67  per  cent,  of  the  fat  in  the  whole 
milk  was  recovered  in  the  butter.  This  butter  on  the 
average  contained  82.37  per  cent,  butter  fat;  in  other 
words,  117.3  pounds  of  butter  were  made  from  each  100 
pounds  of  butter  fat  in  the  whole  milk.^  The  exact  con- 
version factor  would  be  1.173.  As  this  is  an  awkward 
number  to  use,  and  as  1^  is  so  nearly  the  same  ...  it 
has  seemed  best  to  recommend  that  the  latter  be  used  as 
the  conversion  factor." 

A  resolution  was  adopted  by  this  association  recom- 
mending that  the  approximate  equivalent  of  butter  be 
computed  by  multiplying  the  amount  of  butter  fat  by  1^. 

These  figures  are  the  result  of  more  than  ordinary  care 
in  skimming,  churning  and  testing,  and  probably  repre- 
sent the  minimum  losses  of  fat  in  the  manufacturing  pro- 
cesses. The  increase  of  churn  over  test  represented  by 
one-sixth,  or  16  per  cent.,  may  therefore  be  taken  as  a 
maximum  ''overrun"  under  ordinary  factory  conditions. 
Butter  makers  who  report  overruns  of  16-20  per  cent,  do 
not  show  their  expertness  in  butter  making  by  such  high 
figures,  but  their  lack  of  accuracy  in  testing,  or  careless- 
ness in  working  the  butter;  a  large  overrun  may  be  ob- 
tained both  by  reading  the  test  too  low,  and  by  leaving 
an  excess  of  water  in  the  butter,  through  insufficient 
working  or  other  causes. 

219.  Butter  yield  from  milk  of  different  richness,  a.  Use 
of  butter  chart.  The  approximate  yield  of  butter  from 
milk  of  different  richness  is  shown  in  table  XI  in  the 


1  When  82  37  fts.  of  butter  fat  will  make  100  lbs.  of  butter,  how  much 
butter  will  96.67  ft>s.  of  butter  fat  make?    82.37  :  96.67  :  :  100  :  x,  x  =  117.3. 


Calculation  of  Butter-  and  Cheese  Yield.  185 

Appendix.  This  table  is  founded  on  ordinary  creamery 
experience  and  will  be  found  to  come  near  to  actual 
every-day  conditions  of  creameries  where  modern  meth- 
ods are  followed  in  the  handling  of  the  milk  and  its  pro- 
ducts. The  table  has  been  prepared  in  the  following 
manner: 

It  is  assumed  that  the  average  loss  of  fat  in  the  skim  milk  is 
.20  per  cent.,  and  that  85  fts.  of  skim  milk  is  obtained  from 
each  100  lbs.  of  whole  milk;  to  this  loss  of  fat  is  added  that  from 
the  butter  milli;  about  10  lbs.  of  butter  milk  is  obtained  per  100 
lbs.  of  whole  milk,  testing  on  the  average  .30  per  cent. 

If/ designate  the  fat  in  100  lbs.  of  milk,  then  the  fat  recov- 
ered in  the  butter  from  100  lbs.  of  milk  will  be 

f-(^X.20+^X.30)  =  f.-.20 

There  is,  on  the  other  hand,  an  increase  in  weigth  in  the 
butter  made,  owing  to  the  admixture  of  non-fatty  components 
therein,  principally  water  and  salt.  Butter  packed  and  ready 
for  the  market  will  contain  in  the  neighborhood  of  84  per  cent, 
of  fat  (213),  so  that  the  fat  recovered  in  the  butter  must  be  in- 
creased by  L04'>  =  1.19.  If  B  therefore  designate  the  yield  of  but- 
ter from  100  lbs.  of  milk,  the  following  formula  will  express  the 
relation  between  yield  and  fat  content,  provided  there  are  no 
other  factors  entering  into  the  problem,  viz. : 
B  =  (f-.20)  1.19 

Certain  mechanical  losses  are,  however,  unavoidable  in  the 
creamery,  as  in  all  other  factory  operations,  viz.,  milk  and 
cream  remaining  in  vats  and  separators,  butter  sticking  to  the 
walls  of  the  churn,  etc.  These  losses  have  been  found  to  aver- 
age about  3  per  cent,  of  the  total  fat  in  the  milk  handled,  under 
normal  conditions  and  under  good  management  (218);  we 
therefore  deduct  this  amount  from  the  preceding  value  for  B, 
and  have: 

B  =  (f-.20)  1.16 

220.  Table  XI  in  the  Appendix,  founded  on  this  form- 
ula, may  be  used  to  determine  the  number  of  pounds  of 


186  Testing  Milk  and  Its  Products. 

butter  which  milk  containing  3  to  5.3  per  cent,  fat  will 
be  likely  to  make.  It  presupposes  good  and  careful 
work  at  the  separator,  churn  and  butter  worker,  and 
under  such  conditions  will  generally  show  yields  of 
butter  varying  but  little  from  those  actually  obtained. 
It  may  be  conveniently  used  by  the  butter  maker  or  the 
manager  to  check  the  work  in  the  creamery;  the  average 
test  of  the  milk  received  during  a  certain  period  is  found 
by  dividing  the  total  butter  fat  received,  by  the  total 
milk,  and  multiplying  the  quotient  by  100;  the  amount 
of  butter  which  the  total  milk  of  this  average  fat  content 
will  make,  according  to  the  table,  is  then  compared  with 
the  actual  churn  yield. 

Example:  A  creamery  receives  200,000  lbs.  of  milk  during 
a  month;  the  milk  of  each  patron  is  tested  and  the  fat  con- 
tained therein  calculated.  The  sura  of  these  amounts  of  fat 
may  be  7583  lbs.;  the  average  test  of  the  milk  is  then  3.79 
percent.  According  to  table  XT,  10,000  fts.  of  milk,  testing3.8, 
will  make  418  Itjs.  of  butter,  and  200,000  Itjs.,  therefore,  8360  lbs. 
of  butter.  The  total  quantity  of  butter  made  during  the  month 
will  not  vary  appreciably  from  this  figure  if  the  work  in  the 
creamery  has  been  properly  done. 

221.  b.  Ise  of  overrun  table.  The  table  referred  to 
above  gives  a  definite  calculated  butter  yield  for  each 
grade  of  milk,  according  to  average  creamery  conditions. 
As  it'  may  be  found  that  this  table  will  give  uniformly 
either  too  low  or  too  high  results,  table  XII  in  i\i^  Appendix 
is  included,  by  means  of  which  the  butter  yield  cor- 
responding to  overruns  from  10-20  per  cent,  may  be 
ascertained  in  a  similar  way  as  above  described. 

The  total  yield  of  butter  is  divided  by  the  total  num- 
ber of  pounds  of  fat  delivered;  the  quotient  will  give  the 


Calculation  of  Butter-  and  Cheese  Yield.  187 

amount  of  butter  made  from  one  pound  of  fat,  and  this 
figure  multiplied  by  the  fat  delivered  by  each  patron 
shows  the  pounds  of  butter  to  be  credited  to  each  patron. 
To  use  the  table,  find  in  the  upper  horizontal  line  the 
number  corresponding  most  nearly  to  the  number  of 
pounds  of  butter  from  one  pound  of  fat.  The  vertical 
column  in  which  this  falls  gives  the  pounds  of  butter 
from  100  lbs.  of  milk  containing  the  per  cents,  of  fat 
given  in  the  outside  columns  (Babcock^). 

B. — Calculation  of  Yield  of  Cheese. 

222.  a.  From  fat.  The  approximate  yield  of  green 
Cheddar  cheese  from  100  lbs.  of  milk  may  be  found  by 
multiplying  the  per  cent,  of  fat  in  the  milk  by  2.7;  if/ 
designate  the  per  cent,  of  fat  in  the  milk,  the  formula 
will,  therefore,  be: 

Yield  of  cheese =2.7  f. (I) 

The  factor  2.7  will  only  hold  good  as  the  average  of  a 
large  number  of  cases.  In  extensive  investigations  dur- 
ing three  consecutive  years,  Van  Slyke^  found  that  the 
number  of  pounds  of  green  cheese  obtained  for  each 
pound  of  fat  in  the  milk  varied  from  2.51  to  3.06,  the 
average  figures  for  the  three  years  1892-'94,  incl., 
being  2.73,  2.71,  and  2.72  lbs.  respectively.  The  richer 
kinds  of  milk  will  produce  cheese  richer  in  fat,  and 
will  yield  a  relatively  larger  quantity  of  cheese,  pound 
for  pound,  than  poor  milk,  for  the  reason  that  an  in- 
crease in  the  fat  content  of  milk  is  accompanied  by  an 


1  Woll,  Handbook  for  Farmers  and  Dairymen,  p.  307. 

2  N.  Y.  experiment  station  (Geneva),  bulletins  No.  65  and  82. 


188  Testing  Milk  and  Its  Products. 

increase  in  the  other  cheese-producing  solids  of  the  milk.' 
The  preceding  formula  would  not,  therefore,  be  correct 
for  small  lots  of  either  rich  or  poor  milk,  but  only  for 
milk  of  average  composition,  and  for  large  quantities  of 
normal  factory  milk.  For  cured  cheese  the  factor  will 
be  somewhat  lower,  viz.,  about  2.6,  on  the  average. 

223.  b.  From  solids  not  fat  and  fat.  If  the  percentages 
of  solids  not  fat  and  of  fat  in  the  milk  are  known,  the 
following  formula  by  Babcock  will  give  close  results: 

Yield  of  green  cheese  =  1.58(^-|-+. 91  f  )  .  .  (II) 
8  being  the  per  cent,  of  solids  not  fat  in  the  milk,  and/ 
the  per  cent,  of  fat.  • 

The  solids  not  fat  can  be  readily  ascertained  from  the 
lactometer  reading  and  the  per  cent,  of  fat,  as  shown  on 
p.  100,  by  means  of  table  VI  in  the  Appendix. 

Table  XIII  in  the  Appendix  gives  the  yield  of  cheese 
from  100  lbs.  of  milk  containing  from  2.5  to  6.0  percent, 
fat,  the  lactometer  readings  of  which  range  between  26 
and  36.  By  means  of  this  table  cheese  makers  can  cal- 
culate very  closely  the  yields  of  cheese  which  certain 
quantities  of  milk  will  make;  as  it  takes  into  considera- 
tion the  non-fatty  solids  as  well  as  the  fat  of  the  milk, 
the  results  obtained  by  the  use  of  this  formula  will  be 
more  correct  than  those  found  by  means  of  formula  (I). 
The  uncertain  element  in  the  formula  lies  in  the  factor 


1  Investigation  as  to  the  relation  between  the  quality  of  the  milk  and 
the  yield  of  cheese  have  been  conducted  by  a  number  of  experiment  sta- 
tions; the  following  references  give  the  main  contributions  published  on 
this  point;  N.  Y  (Geneva)  exp.  station,  reports  10-13,  incl.;  Wis.  exp.  sta., 
reports  11  and  12;  Ont.  Agr.  College,  reports  1894-'96,  incl;  Minn.  exp.  sta., 
b.  19,  reports  1892-'94,  inch;  Iowa  exp.  sta.,  bull.  21;  Hoards  Dairyman,  1892, 
p.  2400. 

2  For  derivation  of  this  formula,  see  Wisconsin  experiment  station, 
twelfth  report,  p.  105. 


Calculation  of  Butter-  and  Cheese  Yield.  189 

1.58,  which,  as  shown  above,  is  based  on  an  average  water* 
content  of  37  per  cent,  in  the  green  cheese.  This  may, 
however,  be  changed  to  suit  any  particular  case,  e.  g.,  35 
percent  (Y^^  =  1.54),  40  per  cent.  (Jg%Q-=1.67),  etc.  The 
average  percentages  of  water  in  green  cheese  found  by 
Van  Slyke  in  his  investigations  referred  to  above,  were 
for  the  years  1892-'94,  respectively,  36.41,  37.05  and 
36. 70  per  cent. 

224.  c.  From  casein  and  fat.  If  the  percentages  of 
casein  and  fat  in  the  milk  are  known,  the  yield  of  cheese 
may  be  calculated  by  the  following  formula,  also  pre- 
pared by  Dr.  Babcock: 

Yield  of  cheese  =  1.1  f-f-2. 5  casein      .       .       .     (HI). 
""This  formula  will  give  fairly  correct  results,  but  no 
more  so  than  formula  (II);  it  is  wholly  empirical. 


CHAPTEE  XIII. 
CALCULATINQ  DIVIDENDS. 

A. — Calculating  Dividends  at  Creameries. 

225.  The  simplest  method  of  calculating  dividends  at 
creameries  is  to  find  the  number  of  pounds  of  butter  fat 
delivered  to  the  creamery  by  each  patron  for  a  certain 
length  of  time,  and  then  multiply  this  number  by  the 
price  per  pound  of  fat.  Farmers  are  usually  paid  once 
a  month  for  their  milk  at  the  factory.  Each  lot  of  milk 
is  weighed  when  delivered  at  the  creamery,  and  a  small 
quantity  thereof  is  saved  for  the  composite  sample,  as 
previously  explained  under  Composite  tests  (176). 
Some  creameries  test  these  samples  at  the  end  of  each 
week,  and  others  after  collecting  them  for  ten  days  or 
two  weeks.  If  the  four  weekly  composite  samples  of  a 
patron's  milk  tested  3.8,  4.0,  3.9,  4.1  per  cent.,  these 
four  tests  are  added  together,  and  the  sum  divided  by  4; 
the  result,  3.95  per  cent.,  is  used  as  the  average  test  of 
this  milk.  By  multiplying  the  total  number  of  pounds 
of  milk  delivered  by  this  patron,  by  his  average  test,  the 
total  weight  in  pounds  of  butter  fat  delivered  to  the  fac- 
tory during  the  month  is  obtained.  This  weight  of  fat  is 
then  multiplied  by  the  price  to  be  paid  by  the  creamery 
per  pound  of  butter  fat;  the  product  shows  the  amount 
of  money  due  this  patron  for  the  milk  delivered  during 
the  time  samples  were  taken. 

226.  Price  per  pound  of  butter  fat.  The  method  of  ob- 
taining the  price  to  be  paid  for  one  pound  of  butter  fat 


Calculating  Dividends.  191 

varies  somewhat  in  different  creameries,  on  account  of 
the  different  ways  of  paying  for  the  cost  of  manufacturing 
the  butter.  The  method  to  be  followed  is  generally  deter- 
mined by  agreement  between  the  manufacturer  and  the 
milk  producers,  in  case  of  proprietary  creameries,  or  be- 
tween the  shareholders,  in  co  operative  creameries.  The 
following  methods  of  paying  for  the  cost  of  manufacture 
are  at  the  present  time  met  with  in  American  creameries. 

227.  I.  Proprietary  creameries.  First.  —When  the 
creamery  is  owned  by  some  one  person  or  company,  the 
owner  or  owners  agree  to  make  the  butter  for  about  3  cents 
a  pound;  the  difference  between  the  total  receipts  of  the 
factory  and  the  amount  due  the  owner  is  then  divided 
between  the  different  patrons,  according  to  the  amount  of 
butter  fat  contained  in  the  milk  which  they  delivered. 

In  the  majority  of  cases,  the  price  charged  for  making 
butter  is  now  3  cents  a  pound;  2 J  and  2 J  cents  are  some- 
times charged.  The  larger  the  amount  of  milk  received 
at  a  factory,  the  lower  will  naturally  be  the  cost  of  man- 
ufacturing the  butter.^ 

Second. — The  proprietor  of  the  creamery  sometimes 
agrees  to  pay  a  certain  price  for  100  lbs.  of  milk  deliv- 
ered, according  to  its  fat  content,  the  price  of  milk  con- 
taining 4  per  cent,  of  butter  fat  being  the  standard.  This 
price  may  change  during  the  different  seasons  of  the  year 
by  mutual  agreement. 

Third. — A  creamery  owner  may  offer  to  pay  1  to  2 
cents,  usually  1^  cents  below  the  average  market  price  of 
butter,  for  each  pound  of  butter  fat  received  in  the  milk. 

228.  II.  Co-operative  creameries.  In  this  case,  where 
the  creamery  is  owned  by  the  patrons,  one  of  the  stock - 

1  Wisconsin  experiment  station,  bull.  56,  p.  26. 


192  Testing  MUk  and  Its  Products. 

holders  who  is  elected  secretary  attends  to  the  details  of 
runuiDg  the  factory  and  selliag  the  product.  His  ac- 
counts show  the  amount  of  money  received  each  mouth 
for  the  butter  and  other  products  sold,  and  the  expenses 
of  running  the  factory  during  this  time.  The  expenses 
are  subtracted  from  the  receipts,  and  the  balance  is 
divided  among  the  patrons,  each  one  receiving  his  pro- 
portionate share  according  to  the  amounts  of  butter  fat 
delivered  in  each  case  (as  shown  by  the  total  weight  and 
the  average  test  of  milk  delivered  during  this  time). 

In  nearly  all  cases,  the  farmers  receive  about  eighty 
pounds  of  skim  milk  for  each  hundred  pounds  of  whole 
milk  they  deliver  to  the  factory,  in  addition  to  the 
amount  received  for  the  milk,  calculated  according  to 
one  or  the  other  of  the  preceding  methods. 

229.  Illustrations  of  cdlculations  of  dividends.  In  order 
to  illustrate  the  details  of  calculating  dividends,  or  the 
amount  to  be  paid  each  patron  for  the  milk  supplied 
each  month,  when  payments  are  made  by  each  of  the 
four  systems  given,  it  will  be  assumed  that  a  creamery 
receives  5000  pounds  of  milk  daily  for  thirty  days,  and 
makes  6650  lbs.  of  butter  from  the  150,000  lbs.  of  milk 
received  during  this  time.  The  average  test  of  this  milk 
may  be  found  by  multiplying  the  total  weight  of  milk 
delivered  by  each  patron  by  his  average  test,  and  divid- 
ing the  sum  of  these  products  by  the  total  weight  of  milk 
received  at  the  creamery  (in  the  example  given,  by  150,- 
000),  the  quotient  being  multiplied  by  100.  Such  calcu- 
lations may  show  that,  e.  g.,  5700  lbs.  of  butter  fat  have 
been  received  in  all  in  the  milk  delivered  by  the  differ- 
ent  patrons^   this   multiplied   by   100  and  divided  by 


Calculating  Dividends. 


193 


150,000  gives  3.8  as  the  average  test,  or  the  average 
amount  of  butter  fat  in  each  100  lbs.  of  milk  received 
during  the  mouth. 

So  far  the  method  of  calculation  is  common  for  all  dif- 
ferent systems  of  payment  given  above;  the  manner  of 
procedure  now  differs  according  to  the  agreement  made 
between  owner  and  patrons,  or  between  the  shareholders, 
in  case  of  co-operative  creameries. 

230.  I.  First— If  the  net  returns  for  the  6650  ft)S.  of 
butter  sold  during  the  month  were  $1197,  and  the  cream- 
ery is  to  receive  4  cents  per  pound  of  butter  as  the  cost  of 
manufacture,  etc.,  the  amount  due  the  creamery  is 
6650  X. 04  ==$266,  and  the  patrons  would  receive  $1197 — 
$266  =$931.  This  sum,  $931,  is  to  be  paid  to  the  patrons 
for  the  5700  Hds.  of  butter  fat,  which,  as  shown  above, 
was  the  weight  of  fat  contained  in  the  150,000  lbs.  of 
milk  delivered  during  the  month.  The  price  of  one 
pound  of  butter  fat  is  then  easily  found:  $931 -=-5700  = 
16 J  cents.  This  price  is  paid  to  all  patrons  for  each 
pound  of  butter  fat  delivered  in  their  milk  during  the 
month.  The  monthly  milk  record  of  three  patrons  may, 
e.  g.,  be  given  in  the  following  table: 


First  week 

Second  week 

Thirdweek 

Fourth  week 

Total 

Milk 

Rs. 

ii 

Patrons 

.Milk 

fts. 

Test 
pr.ct. 

Milk 

ft)S. 

Test 
per  ct. 

Milk 

It.s. 

Test 
pr.ct. 

MUk 
lbs. 

Test 
per  ct. 

3.45 

.3.7 

3.6 

No.  1 

"    2 

"    3 

350O 

700 

2480 

3.6 
3.8 
4.2 

3000 

665 

2000 

3.5 
3.8 
3.8 

3600 
720 
18.50 

3.65 

3.6 

4.0 

3450 
750 
1500 

13,5.50 

2,825 
7,830 

3.55 
3.73 
3.99 

Multii)lying  each  patron's  total  milk  by  his  average 
test  gives  the  number  of  pounds  of  butter  fat  in  his  milk, 


194 


Testing  Milk  and  Its  Products. 


and  this  figure  multiplied  by  .16J  shows  the  money  due 
for  his  milk,  as  given  below: 


Patron. 

Total  milk 

fts. 

Average  test 
per  cent. 

Butter  fat, 
lbs. 

Price  of  fat 
per  lt>.,  cents. 

Amounts 
due. 

No.  1 

13,550 

2,825 
7,a30 

3.55 
3.7 

3.9 

481.0 
104.5 
3a5. 4 

161..^ 
163^ 
16i.< 

$78.56 

No   2 

17  06 

No.  3 

48.96 

231.  Second. — When  the  proprietor  of  a  creamery 
agrees  to  pay  a  certain  price  for  100  fts.  of  4  per  cent, 
milk,  the  receipts  for  butter  sold  and  the  price  per  pound 
of  butter  do  not  enter  into  the  calculation  of  the  amount 
due  each  patron  for  his  milk;  but  the  weight  and  the 
test  of  each  patron's  milk  are  just  as  important  as  before. 
If  it  is  agreed  to  pay  G6  cents  per  100  lbs.  of  4  per  cent.  - 
milk  (i.  e.,  milk  containing  4  per  cent,  of  butter  fat), 
the  price  of  one  pound  of  butter  fat  will  be  66^4  =  16^ 
cents,  and  the  amount  due  each  patron  is  found  by  multi- 
plying the  total  weight  of  butter  fat  in  his  milk  by  this 
price.  To  facilitate  this  calculation,  so-called  Relative- 
Value  Tables  have  been  constructed,  the  use  of  which  is 
explained  below  (237). 

232.  Third. — If  a  creamery  agrees  to  pay  for  butter  fat, 
say  1^  cents  per  pound  below  the  average  market  price 
of  butter  each  month,  the  price  of  one  pound  of  butter 
fat  is  found  by  averaging  the  market  quotations  and  sub- 
tracting 1^  cents  therefrom.  If  the  four  weekly  market 
prices  were  17  J,  17,  16^  and  19  cents,  the  average  of  these 
would  be  nh  cents,  and  this  less  1-^-  gives  16  cents  as  the 
price  per  pound  of  fat  to  be  paid  to  the  patrons;  this 
price  is  then  u.sed  in  calculating  the  dividends  as  in  case 
of  first  method  (230). 


Calculating  Dividends. 


195 


Patron, 

Total  milk 

lbs. 

Average  test 
per  cent. 

Butter  fat, 
lbs. 

Price  of  fat, 
per  lb.,  cents. 

Amounts 
due. 

No.  1 

13, .550 

2,825 
7  830 

3.55 

3.7 

3.9 

^81.0 
104.5 
305.4 

16 
16 
16 

$76.96 
16  72 

No.  2 

No.  3 

48.86 

233.  II.  If  the  creamery  is  owned  by  the  farmers,  the 
running  expenses  for  a  month  are  subtracted  from  the 
gross  returns  received  for  the  butter,  and  the  price  to  be 
paid  per  pound  of  butter  fat  is  found  by  dividing  the 
amount  left,  by  the  total  number  of  pounds  of  butter  fat 
delivered  during  the  month.  This  price  is  used  for  pay- 
ing each  patron  for  his  milk  according  to  the  amount  of 
fat  contained  therein,  as  already  explained  under  Pro- 
prietary Creameries  (230). 

The  monthly  running  expenses  of  a  co-operative  cream- 
ery generally  include  such  items  as  the  wages  of  the 
butter  maker  (and  manager  or  secretary,  if  these  officers 
are  salaried),  labor  (hauling,  helper,  etc.),  cost  of  butter 
packages,  coal  or  wood,  salt  and  other  supplies,  freight 
and  commission  on  the  butter  sold,  repairs  and  insurance 
on  buildings,  etc.  A  certain  amount  is  also  paid  into  a 
sinking  fund  (say  5  cents  per  100  fts.  of  milk),  which 
represents  the  depreciation  of  the  property,  wear  and 
tear  of  building  and  machinery,  bad  debts,  etc.  These 
items  are  added  together,  and  their  sum  subtracted  from 
the  gross  receipts  for  the  butter  sold  during  the  month. 

234.  Assuming  the  receipts  for  the  butter  during  the 
month  to  be  $1197,  and  the  running  expenses  of  the  fac- 
tory $285,  the  amount  to  be  divided  among  the  patrons 
is  $912;  the  quantity  of  butter  fat  received  was  5700  lbs., 


196  Testing  Milk  and  Its  Products. 

and  the  price  per  pound  of  butter  fat  will  therefore  be  16 
cents.     The  account  will  then  stand  as  given  in  (232). 

235.  Other  systems  of  payment.  Besides  these  four 
systems  of  payment,  there  are  various  other  agreements 
made  between  manufacturer  and  producer,  but  with 
them  all  the  one  important  computation  is  the  price  to 
be  paid  per  pound  of  butter  fiit:  this  forms  the  basis  of 
calculating  the  factory  dividends,  when  milk  is  paid  for 
by  the  Babcock  test. 

236.  Paying  for  butter  delivered.  In  some  instances 
patrons  desire  to  receive  pay  for  the  quantity  of  butter 
which  the  milk  delivered  by  them  will  make.  This  can 
be  ascertained  quite  accurately  from  the  total  receipts 
and  the  total  weights  of  both  butter  fat  and  butter.  The 
total  money  to  be  paid  for  butter  (the  net  receipts)  are 
divided  by  the  number  of  pounds  of  butter  sold,  to  get 
the  price  to  be  paid  per  pound  of  butter;  the  total  yield 
of  butter  divided  by  the  total  amount  of  butter  fat  de- 
livered in  the  milk,  gives  the  amount  of  butter  corre- 
sponding to  one  pound  of  butter  fat,  and  the  pounds  of 
fat  delivered  by  each  patron  is  then  multiplied  by  this 
figure.  This  method  requires  more  figuring  than  those 
given  in  the  preceding,  and  the  dividends  are  no  more 
accurate,  in  fact  less  so,  than  when  calculations  are  based 
on  the  price  per  pound  of  fat. 

237.  Relative  value  tables.  These  tables  give  many  of 
the  multiplications  used  in  computing  the  amount  due 
for  various  weights  of  milk  testing  from  3  to  6  per  cent, 
of  fat.  They  can  be  easily  constructed  by  any  one  as 
soon  as  the  price  of  one  pound  of  fat  is  determined  in 
each  case.     If  the  price  to  be  paid  per  pound  of  fat  i 


Calculating  Dividends. 


197 


say  15  cents,  the  value  of  each  100  lbs.  of  milk  of  differ- 
ent quality  is  found  by  multiplying  its  test  by  15.  If  the 
average  tests  of  the  different  patrons'  milk  vary  from  3 
to  5  per  cent.,  the  relative- value  table  would  be  as 
follows: 


3.0xl5=45c.  per  100  lbs. 

3.1xl5=46.5c. 

3.2xl5=48c 

3.3Xl5=49.5c. 

3.4xl5=51c. 

3.5xl5=52.5c. 


3.Gxl5=54c.  per  100  lbs. 
3.7Xl5=55.5c.         " 
3.8xl5=57c. 
3.9xl5=r58.5c.         " 
4.0xl5=60c. 

etc. 


By  continuing  this  multiplication,  or  adding  the  mul- 
tiplier each  time  for  each  tenth  of  a  per  cent,  up  to  5  per 
cent,  of  fat,  a  table  is  made  that  can  be  used  for  calcu- 
lating the  amount  due  per  100  Hbs.  of  milk,  at  this  price 
per  pound,  and  the  weight  of  milk  delivered  by  each 
patron  is  multiplied  by  the  price  per  100  lbs.  of  milk 
shown  in  the  table  opposite  the  figure  representing  his 
test. 

Example:  A  patron  supplies  2470  lbs.  of  milk,  testing  3.2 
per  cent,  of  fat;  price  per  pound  of  fat,  15  cents;  he  should  then 
receive  24.70x.48=$11.85  (see  above  table).  Another  patron 
delivering  3850  lbs.  of  milk  testing  3.8  per  cent,  will  receive,  at 
the  same  price  per  pound  of  fat,  38.50 x. 57=121.94. 

The  relative  value  tables  in  the  Appendix  give  the 
price  per  100  lbs.  of  milk  testing  between  3  and  6  per 
cent,  fat,  when  the  price  of  three  per  cent,  milk  varies 
from  30  to  90c.  per  100  lbs.  In  using  the  tables,  first 
find  the  figure  showing  the  price  which  it  has  been  de- 
termined to  pay  for  100  lbs.  of  milk  of  a  certain  quality, 
say  3  or  4  per  cent.- mil kj  the  figures  in  the  same  vertical 
column  then  give  the  price  to  be  paid  per  100  lbs.  of 
milk  testing  between  3  and  6  per  cent. 


198 


Testing  Mill-  and  Its  Products. 


Example  1:  It  has  been  decided  to  pay  90  cents  per  100  Itjs. 
of  4  per  cent. -milk.  The  figure  90  is  then  sought  in  the  table  in 
the  same  line  as  4.0  percent.,  and  the  vertical  column  in  which 
it  is  found  gives  the  price  per  100  lbs.  of  3  to  6  per  cent. -milk, 
3.8  per  cent.-milk  is  thus  worth  85  cents  per  100  lbs.  and  4.5  per 
cent-milk,  $1.01,  under  the  conditions  given.  The  prices  of 
milk  of  other  qualities  are  found  in  the  same  way. 

Example  2:  In  the  example  referred  to  under  Illustrations 
of  calculating  creamery  dividends  (I  b,  231),  the  figures  for  the 
patrons  Nos.  1,  2  and  3,  would  be  as  follows: 


Patron. 

Milk  delivered, 
fts. 

Average 
test. 

Price  per  100  fts. 
of  milk,  cents. 

Amounts 
due. 

No.  1 

13,550 

2,825 
7,830 

3.55 

3.7 

3.9 

58.5 
61.0 
64.0 

§•79. 26 

"   2 

17  23 

"3 

50  11 

238.  Milk-  and  cream  dividends.  When  cream  from 
farm  hand  sepa.rators  or  other  sources  is  brought  to  a 
factory  receiving  and  skimming  whole  milk,  the  cream 
patron's  dividend  should  be  calculated  a  little  differently 
than  that  of  the  milk  patron. 

In  one  case  the  dividend  is  based  on  the  weight  and  the 
test  of  cream  and  in  the  other  on  the  weight  and  the  test 
of  milk;  the  difference  between  the  two  being  represented 
by  the  fat  left  in  the  factory  skim  milk.  This  skim  milk 
fat  is  included  in  the  milk  patron's  dividend, and  conse- 
quently ought  also  to  be  allowed  for  in  calculating  the 
amount  due  the  cream  patron.  Such  an  allowance  can 
be  fairly  made  by  multiplying  the  cream  fat  by  1.03. 
This  is  assuming  that  the  one-tenth  or  more  of  fat  re- 
turned to  the  milk  patron  in  his  skim  milk  is  about 
three  per  cent,  of  the  total  fat  in  his  whole  milk. 

Both  milk  and  cream  patron  suffer  the  same  manufac- 
turing loss  in  the  factory  butter  milk  so  that  an  equaliza- 


Calculating  Dividends.  199 

tion  of  the  skimming  losses  is  all  that  is  necessary  in  order 
to  put  both  on  a  uniform  basis  for  calculating  dividends. 

239.  The  following  illustration  may  help  to  make  these 
calculations  clearer.  Milk  patron  No.  1  may  deliver  to 
the  creamery  during  the  month  5320  lbs.  of  milk  testing 
3.8  per  cent. fat,  which  therefore  contains  [  ^^^Jj^^)=202 
lbs.  butter  fat.  If  the  price  paid  the  patrons  is  20c 
then  the  202  ITbs.  x20c  amounts  to  $40.40,  the  money  due 
this  patron  for  his  milk.  If,  however,  another  patron 
sent  485  lbs.  of  cream  testing  22.0  per  cent,  fat  to  the 
same  factory  during  the  month,  the  weight  of  fat  in  the 
cream  is  first  found  in  the  same  way  as  in  the  milk. 
{^^^)^10Q,7  lbs.  butter  fat.  Now  instead  of  multi- 
tiplying  this  butter  fat  by  20c  as  was  done  for  the  milk 
patron  it  must  first  be  multiplied  by  1.03  which  makes 
the  necessary  allowance  for  the  skim  milk  fat  that  the 
milk  patron  was  paid  for.  106.7  X  1.03  —  109.9  lbs.  but- 
ter fat  which  is  now  multiplied  by  20c  per  pound,  giving 
$21.98.  This  is  the  amount  due  the  cream  patron  when 
both  milk  and  cream  are  received  at  the  same  factory 
and  the  cream  from  both  patrons  is  churned  together.  ^ 
B. — Calculating  Dividends  at  Cheese  Factories. 

240.  The  amount  of  cheese  made  from  a  certain  quan- 
tity of  milk  depends,  as  before  shown,  in  a  large  measure 
on  the  richness  of  the  milk  in  butter  fat  (222).  Rich  milk 
will  give  more  cheese  per  hundred  weight  than  poor  milk, 
and  within  the  ordinary  limits  of  normal  factory  milk  the 
increased  yields  will  be  nearly,  but  not  entirely,  pro- 
portional to  the    fat  contents  of  the  different  kinds  of 

1  I7th  Report  Wis,  expt.  station,  p.  90;  20th  report,  pp.  130-131. 


200  Testing  Milk  and  Its  Products. 

milk.  Since  the  quality  of  the  cheese  produced  from 
rich  milk  is  better  than  that  of  cheese  made  from  thin 
milk  and  will  demand  a  higher  price,  it  follows  that  no 
injustice  is  done  by  rating  the  value  of  milk  for  cheese 
production  by  its  fat  content.  This  subject  has  been 
discussed  frequently  during  late  years  in  experiment 
station  publications  and  in  the  dairy  press  (222).  Among 
others,  Babcock  has  shown  that  the  price  of  cheese 
stands  in  a  direct  relation  to  its  fat  content.^  Prof.  Eob- 
ertson,  Commissioner  of  Agriculture  of  Canada,  is  author- 
ity for  the  statement  that  the  quality  of  the  cheese  made 
from  milk  containing  3.0  to  4.0  per  cent,  of  fat  was  in- 
creased in  value  by  one-eight  of  a  cent  per  pound  for 
every  two- tenths  of  a  per  cent,  of  fat  in  the  milk,-  a 
figure  which  is  fully  corroborated  by  Dr.  Babcock' s 
results.  The  injustice  of  the  'Spooling  system",  by 
which  all  kinds  of  milk  receive  the  same  price,  is  evi- 
dent from  the  preceding;  if  the  milk  of  a  certain  patron 
is  richer  than  that  of  others,  it  will  make  a  higher  grade 
of  cheese,  and  more  of  it  per  hundredweight;  hence  a 
higher  price  should  be  paid  for  it. 

Payment  on  the  basis  of  the  fat  content  of  milk  is, 
therefore,  the  most  equitable  method  of  valuing  milk  for 
cheese  making,  and  in  case  of  patrons  of  cheese  factories 
as  with  creamery  patrons,  dividends  should  be  calcu- 
lated on  the  basis  of  the  results  obtained  by  testing  the 
milk  delivered.  The  testing  may  be  conveniently  ar- 
ranged by  the  method  of  composite  sampling,  in  the  way 
already  described  for  creameries  (176). 

1  Wisconsin  exp,  station,  Uth  report,  p.  134. 

2  Hoard's  Dairyman,  March  29,  1895. 


Calculating  Dividends.  201 

241.  Calculation  of  dividends.  As  with  creameries,  the 
first  thing  to  be  ascertained  is  the  price  to  be  paid  per 
pound  of  butter  fat.  The  factory  records  should  show 
the  number  of  pounds  of  cheese  made  from  the  total  milk 
delivered  to  the  factory  during  a  certain  time,  generally 
one  month,  and  the  money  received  for  this  cheese.  The 
cost  of  making  the  cheese  and  all  other  expenses  that 
should  be  paid  for  out  of  the  money  received  for  the 
cheese,  are  deducted  from  the  total  receipts,  and  the  dif- 
ference is  divided  among  the  patrons  in  proportion  to 
the  amounts  of  butter  fat  delivered  in  the  milk. 

The  weights  of  the  milk  delivered  and  the  tests  of  the 
composite  samples  furnish  data  for  calculating  the  quan- 
tities of  butter  fat  to  be  credited  to  each  patron.  The 
money  to  be  paid  to  the  patrons  is  then  divided  by  the 
total  weight  of  butter  fat  delivered  to  the  factory  and  the 
price  of  one  pound  of  fat  thus  obtained.  The  money  due 
each  patron  is  now  found  by  multiplying  the  total  num- 
ber of  pounds  of  butter  fat  in  his  milk  by  this  price  per 
pound. 

The  illustrations  already  given  for  calculating  patrons' 
dividends  at  creameries  according  to  the  various  methods 
will  serve  equally  well  to  show  the  manner  in  which 
dividends  are  calculated  at  a  cheese  factory.  For  the 
sake  of  clearness  an  example  is  given  that  applies  directly 
to  cheese  factories. 

242.  Illustration  of  calculation  of  dividends.  It  may 
be  assumed  that  15,000  fbs.  of  green  cheese  is  made 
from  150,000  lbs.  of  milk  delivered  to  a  factory  in  a 
month.  According  to  the  weighings  and  the  tests  made, 
the  milk  contained  5,700  lbs.  of  butter  fat.    If  the  cheese 


202 


Testing  Milk  and  Its  Products. 


sold  at  an  average  price  of  7^  cents  a  pound,  the  gross 
receipts  would  be  $1 ,  125. 00.  The  amount  to  be  deducted 
from  the  gross  receipts  will  depend  on  the  agreement 
made  between  the  factory  operator  and  the  patrons,  in 
case  of  proprietary  cheese  factories,  or  between  the 
shareholders  and  the  maker,  when  the  factory  is  run  on 
the  co-operative  plan.  As  before  we  shall  consider  these 
systems  separately. 

243.  I.  Proprietary  cheese  factories.  The  owner  of  the 
factory  generally  agrees  to  make  the  cheese  for  a  certain 
price  per  pound  and  to  pay  the  patrons  what  is  left  after 
deducting  this  amount.  If  the  price  agreed  on  is  1^ 
cents  per  pound  of  green  cheese,  this  would  amount  to 
8225  in  the  example  given.  Subtracting  this  sum  from 
the  gross  receipts,  81,125,  leaves  $900,  which  is  to  be 
paid  the  patrons.  The  total  amount  of  butter  fat  deliv- 
ered by  the  patrons  was  5, 700  lbs. ;  hence  the  price  of  one 
pound  of  butter  fat  will  be  900^5,700  =  . 1577,  or  15.8 
centfe.  Taking  the  figures  for  the  three  patrons  already 
mentioned  under  Creamery  Dividends,  we  then  have: 


Patron. 

Total  milk, 

lt.s. 

Average 

test, 
per  cent. 

Butter  fat, 
lbs. 

Price  per  ft. 
of  fat, 
cents. 

Amounts 
due. 

No.  1 

13,5.50 

2,825 
7,830 

3.55 

3.7 

3.9 

481.0 
104.5 

305.-1 

15.8 
15.  S 
15.8 

$76.00 

No.  2 

16.51 

.No.  3 

48. 25 

244.  II.  Co-operative  cheese  factories.  The  method 
of  payment  at  co-operative  cheese  factories  is  nearly  the 
same  as  that  already  given,  except  that  a  certain  sum 
representing  the  expenses  is  subtracted  from  the  gross 
receipts  for  the  cheese,  and  the  balance  is  divided  among 


Calculating  Dividends.  203 

the  patrons  according  to  the  amount  of  butter  fat  fur- 
nished by  each,  in  the  same  manner  as  in  the  above  case, 
after  the  price  of  a  pound  of  fat  has  been  obtained. 

The  price  per  100  lbs.  of  milk  can  be  calculated  in  the 
same  way  as  at  creameries,  by  multiplying  the  test  of 
each  lot  by  the  price  per  pound  of  fat.  ^ 


1  Suggestions  regarding  the  organization  of  co-operative  creameries 
and  cheese  factories  will  be  found  in  the  Appendix,  following  Table  XV, 
Draft  of  constitution  and  by-laws  for  co-operative  factory  associations  are 
also  given  in  the  Appendix.  It  is  hoped  that  these  will  prove  helpful  to 
farmers  who  contemplate  forming  such  associations. 


CHAPTER  XIV. 
CHEIVIICAL  ANALYSIS  OF  MILK  A^D  ITS  PRODUCTS. 

245.  An  outline  of  the  methods  followed  in  determin- 
ing quantitatively  the  main  components  of  milk  and  its 
products  is  given  in  the  following  for  the  guidance  of 
more  advanced  dairy  students.  This  work  cannot  be 
done  outside  of  a  fairly  well- equipped  chemical  labora- 
tory, or  by  persons  who  have  not  been  accustomed  to 
handling  delicate  chemical  apparatus  and  glassware, 
analytical  balances,  etc.,  and  who  have  not  a  knowledge 
of,  at  least,  the  elements  of  chemistry  and  chemical 
reactions. 

A. — Milk. 

246.  In  a  complete  milk  analysis,  the  specific  gravity 
of  the  milk  is  determined,  and  the  following  milk  com- 
ponents: water,  fat,  casein  and  albumen,  milk  sugar, 
and  ash.  The  methods  of  analysis  described  in  the  fol- 
lowing are  those  used  in  the  chemical  laboratory  of  the 
Wisconsin  experiment  station,  which  in  the  main  are  the 
same  as  those  adopted  by  the  Association  of  Official 
Agricultural  Chemists,  and  with  but  slight  modifications, 
in  general  use  in  the  chemical  laboratories  of  all  Ameri- 
can experiment  stations  and  agricultural  colleges.^ 

247.  a.  Specific  gravity  is  determined  by  means  of  a 
picnometer  or  specific- gravity  bottle,  since  more  accurate 


iThe  methods  of  analysis  adopted  by  the  Association  of  Official  Agri- 
cultural Chemists  are  published  by  the  Chemical  Division  of  the  U.  S. 
Department  of  Agnp.uUure;  see  Bull.  No,  4fi.  revised  edition,  p.  54. 


Chemical  Aaalyufi  of  Milk  and  Its  Products.       205 

results  will  thus  be  reached  than  by  using  an  ordinary 
Queveune  lactometer.  A  thermometer  is  ground  into 
the  neck  of  the  specific-gravity  bottle  so  as  to  form  a 
stopper,  and  the  bottle  is  provided  with  a  glass  stoppered 
side-tube,  to  furnish  an  exit  for  the  liquid  on  expanding. 
A  specific-gravity  bottle  holding  100  grams  of  water  is 
preferably  used.  The  empty  and  scrupulously  cleaned 
bottle  is  first  weighed  on  a  chemical  balance.  The  bot- 
tle is  then  filled  with  recently-boiled  distilled  water  of  a 
temperature  below  60°  F.  (15.5°  C);  the  thermometer 
is  inserted,  and  the  bottle  is  warmed  slightly  by  immers- 
ing it  for  a  moment  in  tepid  water  and  left  standing  uLtil 
the  thermometer  shows  60°  F. ;  the  opening  of  the  side 
tube  is  then  wiped  off  and  closed  with  the  stopper,  and 
the  water  on  the  outside  of  the  bottle  and  in  the  groove 
between  its  neck  and  the  thermometer  is  wiped  oft'  with 
filter  paper  or  a  clean  handkerchief,  when  the  bottle  is 
again  weighed.  The  weight  being  recorded,  the  bottle  is 
emptied  and  dried  in  a  water  oven,  or  if  sufiicient  milk 
is  at  hand,  the  bottle  is  repeatedly  rinsed  with  the  milk, 
the  specific  gravity  of  which  is  to  be  determined.  It  is 
then  filled  with  milk  in  a  similar  manner  as  in  case  of 
water;  the  temperature  of  the  milk  should  be  slightly 
below  60°  F.  and  is  slowly  bi  ought  up  to  this  degree 
after  the  bottle  has  been  filled,  proceeding  in  the  same 
way  as  before  with  water;  the  weight  of  the  bottle  and 
milk  is  then  taken. 

The  weights  of  water  and  of  milk  contained  in  the 
specific-gravity  bottle  are  found  by  subtracting  the 
weight  of  the  empty  bottle  from  the  second  and  the  third 
weights,  respectively,  and  the  specific  gravity  of  the  milk 


206  Testing  Milk  and  Its  Products. 

then  found  by  dividing  the  weight  of  the  milk  by  that  of 
the  water. 

Example:    Weight  of  sp.  gr.  bottle+water... 146.9113  grams. 
Weight  of  sp.  gr.  bottle  empty 40.9423       " 

Weight  of  water 99.9690  grams. 

Weight  of  sp.  gr.  bottle+milk 149.8708  grams. 

Weight  of  sp.  gr.  bottle  empty....  46.9423       " 


Weightof  milk 102.9285  grams. 

02 .9280 
99.969 


Sp.gr.  Of  milk='-^-1.0296 


248.  If  a  plain  picnometer  without  a  thermometer  attached, 
is  available,  the  method  of  procedure  is  similar  to  that  described, 
with  the  difference  that  the  temperature  of  the  water  and  of 
the  milk  must  be  brought  to  60°  F.  before  the  picnometer  is 
filled,  or  the  picnometer  filled  with  either  liquid  is  placed  in 
water  in  a  small  beaker,  which  is  very  slowly  warmed  to  60°  F. 
and  kept  at  this  temperature  for  some  time  so  as  to  allow  the 
liquid  in  the  picnometer  to  reach  the  temperature  desired;  the 
temperature  of  the  water  in  the  beaker  is  ascertained  by  means 
of  an  accurate  chemical  thermometer.  The  perforated  stopper 
is  then  wiped  off,  the  picnometer  is  taken  out  of  the  water, 
wiped  and  weighed.  It  is  necessary  to.  weigh  very  quickly  if 
the  room  temperature  is  much  above 60°  F.,  as  in  such  cases  the 
expanding  liquid  will  flow  on  to  the  balance  pan,  with  a  re- 
sultant loss  in  weight  from  evaporation. 

The  weights  of  specific-gravity  bottle  or  picnometer,  empty 
and  filled  with  water,  need  only  be  determined  a  couple  of 
times,  and  the  averages  of  these  weighings  are  used  in  subse- 
quent determinations. 

249.  Westphal  balance.  Where  only  a  small  amount 
of  milk  is  available,  or  in  rapid  work,  the  specific  grav- 
ity may  be  taken  with  considerable  accuracy  by  means 
of  a  Westphal  balance.     The  arrangement  and  use  of 


Chemical  Analysis  of  Milk  and  Its  Products.       207 

this  coDvenient  little  apparatus  is  readily  explained 
verbally. 

For  the  determination  of  the  specific  gravity  of  loppered 
milk,  see  260. 

250.  b.  Water.  The  milk  is  weighed  into  a  perforated 
copper  tube  filled  with  prepared  dry  asbestos.  The  tubes 
are  made  from  perforated  sheet  copper,  with  holes  about 
.7  mm.  in  diameter  and  about  .7  mm.  apart;  they  are 
60  mm.  long,  20  mm.  in  diameter  and  closed  at  the  bot- 
tom. The  asbestos  is  prepared  from  clean  fibrous  asbes- 
tos, which  is  ignited  at  low  heat  in  a  muffle  oven,  treated 
with  a  little  dilute  HCl  (1  :  3)  and  then  with  distilled 
water  till  all  acid  is  washed  out;  it  is  then  torn  in  loose 
layers  and  dried  at  a  low  temperature  in  an  air  bath; 
when  dry  it  can  be  easily  shredded  in  fine  strings  and  is 
placed  in  a  wide- mouth,  glass-stoppered  bottle. 

About  two  grams  of  asbestos  are  placed  in  each  tube, 
packing  it  rather  loosely;  the  tube  is  then  weighed,  a 
small  narrow  beaker  being  inverted  over  it  on  the  scale 
pan.  5  cc.  of  milk  are  now  dropped  on  to  the  asbestos 
from  a  5  cc.  fixed  pipette,  the  beaker  again  placed  over 
the  tube,  and  the  weight  of  the  5  cc.  of  milk  delivered 
H-copper  tube  taken.  The  weight  of  the  milk  is  ob- 
tained by  difference.  The  tubes  are  then  placed  in  a 
steam  oven  and  heated  at  100°  C.  until  they  no  longer 
decrease  in  weight,  which  ordinarily  will  take  about 
three  hours.  Place  in  desiccator  until  cold,  and  weigh ; 
the  difference  between  the  weight  of  the  tube+milk  and 
this  last  weight  gives  the  water  contained  in  the  milk, 
which  is  then  calculated  in  per  cent,  of  the  quantity  of 
milk  weighed  out. 


:208  Testing  Milk  and  Its  Products. 

Example:  Weight  of  tube+beaker+niilk 29.3004  grams. 

Weight  of  tube+beaker 24.1772      " 

Milk  weighed  out 5.1232  grams. 

Weight  of  tube+beaker+milk 29.3004  grams. 

Weight  of  tube-(-beaker-|-milk,  dry  24.9257      " 


Per  cent,  of  water  in  milk =^-^5^^^^ =85. 39  per  cent. 


Weight  of  water 4.3747  grams. 

?747  X  ] 
5.1232 

JVofe.  The  per  cent,  of  total  solids  in  milk  is  often  given, 
instead  of  that  of  water;  this  may  be  readily  obtained  by 
subtracting  the  weight  of  the  empty  tube  from  that  of 
the  tube  filled  with  milk  solids,  and  finding  the  per  cent, 
of  the  milk  weighed  out  which  this  difference  makes.  In 
the  above  example,  the  weight  of  milk  solids  thus  is 
24.9257— 24. 1772  =  .7485  grams,  and  the  per  cent,  of 
total  solids  in  the  milk  =  14.61  per  cent. 

251.  Alternate  method.  Five  cc.  of  milk  are  measured  out  on 
a  weighed  flat  porcelain  dish  (50-60  mm.  in  diameter;  porcelain 
crucible  covei-s  will  answer  the  purpose  better  than  any  other 
vessel  on  the  market,  provided  the  handle  be  broken  off  or 
ground  oflF  level  on  an  emery  wheel);  this  is  weighed  rapidly; 
two  or  three  drops  of  30  per  cent. -acetic  acid  are  added,  and  the 
dish  is  dried  in  a  steam  oven  at  100°  C.  until  no  further  loss  in 
weight  is  obtained.  After  cooling  in  desiccator,  the  weight  of 
the  milk  solids  is  obtained,  and  by  calculation  as  before,  the 
per  cent,  of  water  or  total  solids  in  the  milk. 

252.  c.  Fat.  The  dried  tubes  from  the  water  determi- 
nation are  placed  in  Caldwell  extractors  and  connected 
with  weighed,  numbered  glass  flasks  (capacity,  2-3  oz.); 
the  extractors  are  attached  to  upright  Liebig  condensers 
and  the  tubes  extracted  with  pure  ether,  free  from  water, 
alcohol  or  acid,  until  all  fat  is  dissolved;  4-5  hours'  ex- 
traction is  sufficient  for  whole  milk;  in  case  of  samples  of 


Chemical  Analysis  of  Milk  and  Its  Products.       209 

skiin  milk  it  is  well  to  continue  the  extraction  for  8  hours. 
The  ether  is  then  distilled  off  and  recovered,  and  the 
flasks  dried  in  a  copper  oven  until  constant  weight;  after 
cooling  they  are  weighed,  and  the  amount  of  fat  contained 
in  the  quantity  of  milk  originally  weighed  into  the  tubes 
is  thus  ascertained,  and  the  per  cent,  present  in  the  milk 
calculated. 

Example:  Weight  of  flask  +  fat 15.8039  grams. 

Weightofflask 15.5171       " 

Weight  of  fat 2868  grams. 

Milk  weighed  out 5.1232  grams. 

Per  cent,  of  fat  in  milk='  ^^^.^    =5.60  per  cent. 

253.  d.  Casein  and  albumen.  The  sum  of  these  compo- 
nents is  generally  determined  by  the  Kjeldahl  method.^ 
5  cc.  of  milk  are  measured  carefully  into  a  flat-bottom 
800  cc.  Jena  flask,  20  cc.  of  concentrated  sulfuric  acid 
(C.  P. ;  sp.  gr.,  1.84)  are  added,  and  .7  gram  of  mercuric 
oxid  (or  its  equivalent  in  metallic  mercury) ;  the  mixture 
is  then  heated  over  direct  flame  until  it  is  straw-colored 
or  perfectly  white;  a  few  crystals  of  potassium  perman- 
ganate are  now  added  till  the  color  of  the  liquid  remains 
green.  All  the  nitrogen  in  the  milk  has  then  been  con- 
verted into  the  form  of  ammonium  sulfate.  After  cooling, 
200  cc.  of  ammonia-free  distilled  water  are  added,  20  cc. 
of  a  solution  of  potassium  sulfld  (containing  40  grams 
sulfid  per  liter),  and  a  fraction  of  a  gram  of  powdered 
zinc.  A  quantity  of  semi  normal  HCl- solution,  more 
than  sufficient  to  neutralize  the  ammonia  obtained  in  the 
oxidation  of  the  milk,  is  now  carefully  measured  out 
from   a  delicate   burette    (divided   into  2^^  cc. )  into  an 

1  Fresenius'  Zeitschrift,  22,  p.  366;  U.  S.  Dept.  Agr.,  Chem.  Div.,  bull.  46. 
14 


210  Testing  Milk  and  Its  Products. 

Erienraeyer  flask,  and  the  flask  connected  with  a  distilla- 
tion apparatus.  At  the  other  end,  the  Jena  flask  con- 
taiuing  the  watery  solution  of  the  ammonium  sulfate  is 
connected,  after  adding  50  cc.  of  a  concentrated  soda 
solution  (1  pound  ^'pure  potash"  dissolved  in  500  cc.  of 
distilled  water  and  allowed  to  settle);  the  contents  of  the 
Jena  flasks  are  now  heated  to  boiling,  and  the  distillation 
is  continued  for  forty  minutes  to  an  hour,  until  all 
ammonia  has  been  distilled  over. 

The  excess  of  acid  in  the  Erlenmeyer  receiving- flask 
is  then  accurately  titrated  back  by  means  of  a  tenth- 
normal standard  ammonia-solution,  using  a  cochineal- 
solution^  as  an  indicator.  From  the  amount  of  acid 
used,  the  per  cent,  of  nitrogen  is  obtained;  and  from  it, 
the  per  cent,  of  casein  and  albumen  in  the  milk  by  multi- 
plying by  6.25.  -  The  amount  of  nitrogen  contained  in 
the  chemicals  used  is  determined  by  blank  experiments 
and  deducted  from  the  nitrogen  obtained  as  described. 

Example:  The  weight  of  5  cc.  of  milk  (as  obtained  in  deter- 
mining the  water  in  the  milk)  was  5.1465  grams.  5  cc.  of  stand- 
ard HCl  are  added  to  the  receiver,  and  1.55  cc.  of  ^  alkali- 
solution  are  used  in  titrating  back  the  excess  of  acid.  1.55  cc. 
of  ^  alkali  —^=.51  cc.  -w  acid-solution;  the  ammonia  dis- 
tilled  over  therefore  neutralized  5.00-. 51=4.49  cc.  acid.  By 
blank  trials  it  was  found  that  the  reagents  used  furnished  an 
equivalent  of  .02  cc.  acid  in  the  distillate;  this  quantity  sub- 
tracted from  the  acid-equivalent  of  the  nitrogen  of  the  milk 
leaves  4.47  cc.     1  cc.  serai-normal  HCl-solution  corresponds  to 

N 

7  milligrams  or  .007  grams  of  nitrogen;  4.47cc.  -^  HCl  therefore 


1  Sutton,  Volumetric  Analysis,  4th  edition,  p.  :>1. 

2  The  factor  6.30  or  6.37  is  more  correct  for  the  albuminoids  of  milk,  but 
has  not  yet  been  generally  adopted  (p.  15,  foot  note). 


Chemical  Analysis  of  Milk  and  Its  Products.       211 

represents  .03129  gram  of  nitrogen.  This  quantity  of  nitrogen 
was  obtained  from  the  5.1465  grams  of  milk  measured  out;  the 
milk  therefore  contains  *^^^^^=-608  per  cent  of  nitrogen, 
and  .0608x6.25=3.80  per  cent,  of  casein  and  albumen. 

254.  Casein  and  albumen  may  be  determined  separately 
by  Van  Slyke's  method;^  10  grams  of  milk  are  weighed 
out  and  diluted  with  about  90  cc.  of  water  at  40°-42°  C. 
1.5  cc.  of  a  10  per  cent,  acetic  acid  solution  are  then 
added;  the  mixture  is  well  stirred  with  a  glass  rod  and 
the  precipitate  allowed  to  settle  for  3-5  minutes.  The 
whey  is  decanted  through  a  filter  and  the  precipitate 
washed  two  or  three  times  with  cold  water.  The  nitro- 
gen is  determined  in  the  filter  paper  and  its  contents  by 
the  Kjeldahl  method;  blank  determinations  with  the 
regular  quantities  of  chemicals  and  the  filter  paper  used 
are  made,  and  the  nitrogen  found  therein  deducted. 
The  per  cent,  of  nitrogen  obtained  multiplied  by  6.25 
gives  the  per  cent,  of  casein  in  the  milk. 

255.  Albumen  is  determined  in  the  filtrate  from  the 
casein- precipitate;  the  filtrate  is  placed  on  a  water  bath 
and  heated  to  boiling  temperature  of  water  for  ten  to 
fifteen  minutes.  The  washed  precipitate  is  then  treated 
by  the  Kjeldahl  method  for  the  determination  of  nitro- 
gen; the  amount  of  nitrogen  multiplied  by  6.25  gives  the 
amount  of  albumen  in  the  milk.  The  difference  between 
the  total  nitrogenous  components  found  by  the  Kjeldahl 
method,  and  the  sum  of  the  casein  and  the  albumen,  as 
given  above,  is  due  to  the  presence  in  milk  o'f  a  third 
class  of  nitrogen  compounds  (18). 


1  Bulletin  No.  46,  p.  189,  Chemical  Division,  U.  8.  Dept.  of  Agriculture. 


212  Testing  Milk  and  Its  Products. 

256.  e.  Milk  sugar  is  generally  determined  by  differ- 
ence, the  sum  of  fat,  casein  and  albumen  (total  Nx  6.25), 
and  ash,  being  subtracted  from  the  total  solids.  It  may 
be  determined  directly  by  means  of  a  polariscope,  or 
gravimetrically  by  Fehling's  solution;  only  the  former 
method,  as  worked  out  by  Wiley,  ^  will  be  given  here. 

The  specific  gravity  of  the  milk  is  accurately  deter- 
mined, and  the  following  quantities  of  milk  are  measured 
out  by  means  of  a  100  cc.  pipette  graduated  to  .2  cc.  (or 
a  64  cc.  pipette  made  especially  for  this  purpose,  with 
marks  on  the  stem  between  63.7  and  64.3 cc),  according 
to  the  specific  gravities  given:  1.026,  64.3  cc. ;  1.028, 
64. 15  cc. ;  1. 030,  64. 0  cc. ;  1 .  032,  63. 9  cc. ;  1 .  034,  63. 8  cc. ; 
1.036,  63.7  cc.  These  quantities  refer  to  the  Schmidt- 
Haensch  half-shadow  polariscopes,  standardized  for  a 
normal  weight  of  26.048  grams  of  sugar.  The  milk  is 
measured  into  a  small  flask  graduated  at  100  cc.  and 
102.6  cc. ;  30  cc.  of  mercuric-iodid  solution  (prepared 
from  33.2  grams  potassium  iodid,  13.5  grams  mercuric 
chlorid,  20  cc.  glacial  acetic  acid  and  640  cc.  water)  are 
added;  the  flask  is  filled  to  102.6  cc.  mark  with  distilled 
water,  the  contents  mixed,  filtered  through  a  dry  filter, 
and  when  the  filtrate  is  perfectly  clear,  the  solution  is 
polarized  in  a  200  millimeter  tube.  The  reading  of  the 
scale  divided  by  2,  shows  the  per  cent,  of  lactose  (milk 
sugar)  in  the  milk.  Take  five  readings  of  two  different 
portions  of  the  filtrate,  and  average  the  results. 

257.  f.  Ash.  About  20  cc.  of  milk  are  measured  into 
a  flat-bottom  porcelain  dish  and  weighed;  about  one-half 
of  a  cc.  of  30  per  cent. -acetic  acid  is  added,  and  the  milk 

1  Agricultural  Analysis,  iii,  p.  275;  Am.  Chem.  Jour.,  6,  p.  289  et  seq. 


■    Chemical  Analysis  of  Milk  and  Its  rroducis.       213 

first  dried  on  water  bath  and  then  ignited  in  a  muffle  oven 
at  a  low  red  heat.  Direct  heat  should  not  be  applied  in 
determining  the  ash  of  milk,  since  alkali  chlorids  are 
likely  to  be  lost  at  the  temperature  to  which  milk  solids 
have  to  be  heated  to  ignite  all  organic  carbon. 

Example:  Weight  of  porcelain  disli+niilk 49.0907  grams. 

Weight  of  porcelain  dish 28.3538  grams. 

Weight  of  milk 20.7369  grams. 

Weightofdi8h+miik,afterignition  28.5037  grams. 
Weight  of  dish 28.3538  grams. 


Weight  of  milk  ash 1499  gram. 

Per  cent,  of  ash=  '^^^"^-''^  per  cent. 
The  residue  from  the  determination  of  solids  (251) 
may  also  be  used  for  the  ash  determination. 

258.  Acidity  of  milk.  The  acidity  of  milk  is  conven- 
iently determined  by  means  of  Farrington's  alkaline 
tablets  (see  p.  120),  or  by  one-tenth  normal  soda  solu- 
tion. In  the  latter  case  20  cc.  of  milk  are  measured  into 
a  porcelain  casserole;  a  few  drops  of  an  alcoholic  phe- 
nolphtalein  solution  are  added,  and  soda  solution  is  drop- 
ped in  slowly  from  a  burette  until  the  color  of  the  milk 
remains  uniformly  pinkish  on  agitation.    1  cc.  of  ^  alkali 

corresponds  to  .009  grams  lactic  acid,  or  to  .045  per  cent, 
when  20  cc.  of  milk  are  taken  (see  p.  112). 

B.— Cream,  Skim  milk,  Butter  milk,  Whey,  Con- 
densed MILK. 

259.  The  analysis  of  these  products  is  conducted  in 
the  same  manner  as  in  case  of  whole  milk,  and  the  same 
constituents  are  determined,  when  a  complete  analysis  is 
wanted.     Skim  milk,  butter  milk,  and  whey  generally 


214  Testing  Milk  and  Its  Products. 

contain  only  small  quantities  of  solids,  and  especially  of 
fat,  and  it  is,  therefore,  well  to  weigh  out  a  larger  quan- 
tity than  in  case  of  whole  milk;  if  possible,  toward  10 
grams.  The  acidity  of  sour  milk  and  butter  milk  must 
be  neutralized  with  sodium  carbonate  previous  to  the  dry- 
ing and  extraction,  as  lactic  acid  is  soluble  in  ether  and 
would  thus  tend  to  increase  the  ether-extract  (fat),  if  not 
combined  with  an  alkali  previous  to  the  extraction. 

260.  Specific  gravity  of  butter  milk.  The  specific  grav- 
ity of  butter  milk  (as  well  as  of  sour  or  loppered  milk) 
is  determined  by  Wei  bull's  method;  a  known  volume 
of  the  milk  is  mixed  with  a  certain  amount  (say  10  per 
cent. )  of  ammonia  of  a  definite  specific  gravity,  and  the 
specific  gravity  of  the  liquid  determined  after  thorough 
mixing  and  subsequent  standing  for  an  hour.  If  A  desig- 
nate the  volume  of  butter  milk  taken,  B  that  of  ammo- 
nia, and  C  that  of  the  mixture;  and  if  furthermore  8  de- 
signate the  specific  gravity  of  the  butter  milk,  s,  that  of 
the  ammonia,  and  s.^  that  of  the  mixture,  we  have 

„    Cso— Bb, 


A 

Klein  ^  has  modified  this  method  by  weighing  the 
liquids,  thus  securing  greater  accuracy;  22  to  2-4  per 
cent. -ammonia  is  used,  one  tenth  as  much  being  taken  as 
the  amount  of  milk  weighed  out.  The  results  come  uni- 
formly .0005  too  high,  and  this  correction  should  always 
be  made.  The  following  formula  will  give  the  specific 
gravity  of  the  milk,  which  in  case  of  careful  work  will  be 
accurate  to  one-half  lactometer  degree;  if  the  letters  given 
above  designate  weights  (instead  of  volumes  as  before) 
and  specific  gravities  of  the  liquids,  respectively,  we  have 


1  Milchzeitung,  1896,  p.  056;  see  also  De  Koningh,  Analyst,  1899,  p.  1-12. 


Chemical  Analysis  of  Milk  and  Its  Products.       215 

261.  Condensed  milk.  The  same  methods  are,  in  gen- 
eral, followed  in  the  analysis  of  condensed  milk  as  with 
whole  milk.  Condensed  milk  is  preferably  diluted  with 
five  times  its  weight  of  water  prior  to  the  analysis,  both 
because  such  a  solution  can  be  more  easily  handled 
than  the  undiluted  thick  condensed  milk,  and  the  errors 
of  analysis  are  thereby  reduced,  and  because  the  fat  is 
not  readily  extracted  except  when  the  milk  has  been 
diluted.  The  same  constituents  are  determined  as  in 
case  of  whole  milk,  viz.,  solids,  fat,  casein  and  albumen, 
ash,  milk  sugar,  and  cane  sugar  (if  any  has  been  added 
to  the  milk).  The  cane  sugar  is  determined  by  the  dif- 
ference between  the  solids  not  fat  and  the  sum  of  the 
casein,  albumen,  milk  sugar  and  ash;  if  the  student  has 
a  knowledge  of  the  manipulation  of  the  polariscope  and 
has  had  experience  in  gravimetric  sugar  analysis,  the 
milk  sugar  is  determined  gravimetrically,  and  the  cane 
sugar  by  the  difference  between  the  polariscope  reading 
after  inversion  and  the  milk  sugar  present. 

The  specific  gravity  of  condensed  milk  may  be  determined 
by  a  method  similar  to  that  of  McGill.^  50  gr.  of  the 
thoroughly  mixed  sample  are  weighed  into  a  tared  beaker 
and  washed  with  warm  water  into  a  250  cc.  flask,  cooled 
to  00°,  filled  to  the  mark  and  carefully  mixed.  The 
specific  gravity  of  this  solution  (a)  is  then  taken  and  the 
original  density  is  calculated  by  means  of  the  following 
formula : 

Sp.  gr.  of  condensed  milk=  ^_^^ 

Concentration.  The  extent  of  concentration  of  con- 
densed milk  may  be  determined  approximately  by  the 
formula  devised  by  McGill  (loc.  Mt. ): 

1  Bulletin  54,  Laboratory  Inland  Rev.  Dept.,  Ottawa,  Canada. 


216  Testing  Mill'  and  Its  Products. 

Concentration  (c)  =.^ 
where  a  and  s  designate  the  solids  not  fat  and  specific 
gravity,  respectively,  of  the  condensed  milk,  and  a^  and 
Sj  the  corresponding  data  for  the  milk  used.    If  s^  =1.030 
and  «j  =9  per  cent.,  then  c  =  ^  gives  the  concentration. 

0. — Butter. 

262.  Sampling.  A  four-  to  eight-ounce  sample  of  but- 
ter is  melted  in  a  tightly-closed  pint  fruit  jar,  shaken 
vigorously  and  cooled  until  the  butter  is  hardened,  the 
jar  being  shaken  vigorously  at  short  intervals  during  the 
cooling  so  as  to  keep  the  water  of  the  butter  evenly  dis- 
tributed in  the  mass. 

263.  a.  Determination  of  water.  Small  pieces  of  but- 
ter (about  2  grams  in  all)  are  taken  from  the  sample  by 
means  of  a  steel  spatula  and  placed  in  glass  tubes,  seven- 
eighths  of  an  inch  in  diameter  and  two  and  a  half  inches 
long,  closed  at  the  bottom  by  a  layer  of  stringy  asbestos, 
and  filled  two-thirds  full  of  asbestos  prepared  as  for  milk 
analysis  (250).  The  tubes  are  dried  at  100°  C.  in  a  water 
oven,  until  no  further  loss  in  weight  takes  place,  and  are 
then  cooled  and  weighed.  The  loss  in  weight  shows  the 
per  cent,  of  water  present. 

264.  b.  Fat.  The  tubes  are  placed  in  Caldwell  ex- 
tractors and  extracted  for  four  hours  with  anhydrous 
ether;  the  ether  is  then  distilled  off,  and  the  flasks  dried 
in  the  steam  bath  and  weighed,  the  increase  in  weight 
giving  the  lat  in  the  samples  of  butter  weighed  out. 

265:  c.  Casein.  10  grams  of  butter  are  weighed  into 
a  small  beaker  provided  with  a  lip,  and  treated  twice 
with  about  50  cc.  of  gasoline  each  time;  the  solution  is 


Chemical  Analysis  of  Milk  and  Its  Products.       217 

filtered  ofi",  and  the  residue  transferred  to  a  filter  and 
dried;  its  nitrogen  content  is  then  determined  by  the 
Kjeldahl  method  (253).  The  nitrogen  in  the  filter  and 
the  chemicals  used  is  determined  by  blank  trials  and  de- 
ducted. The  nitrogen  multiplied  by  6.25  gives  the 
casein  in  the  butter. 

266.  d.  Ash.  (1)  10  grams  of  butter  are  weighed  into 
a  porcelain  dish  and  treated  twice  with  gasoline,  as  in  the 
preceding  determination;  the  solution  is  filtered  through 
an  ash-free  (quantitative)  filter,  and  the  filter  when  dry 
is  transferred  to  the  dish.  The  dish  is  heated  in  an  air- 
bath  for  half  an  hour  and  then  placed  in  a  muffle  oven, 
where  the  contents  are  burnt  to  a  light  greyish  ash;  the 
dish  is  now  cooled  in  a  desiccator  and  weighed.  The 
difference  between  this  weight  and  that  of  the  empty  dish 
gives  the  amount  of  ash  in  the  butter  weighed  out. 

267.  (2)  About  two  grams  of  butter  are  weighed  into  a 
small  porcelain  dish,  half  filled  with  stringy  asbestos;  the 
dish  is  dried  for  an  hour  in  the  water  oven,  and  the  fat 
then  set  fire  to  with  a  match,  the  asbestos  fibre  serving 
as  a  wick.  When  the  flame  has  gone  ou^,  the  dish  is 
placed  in  a  muffle  oven,  and  the  residue  burnt  to  a  grey- 
ish ash.  After  cooling,  the  dish  is  weighed,  and  the  per 
cent,  of  ash  in  the  butter  calculated  as  under  method  1. 

268.  Complete  analysis  of  butter  in  the  same  sample. 
About  2  grams  of  the  butter  are  weighed  into  a  platinum 
gooch  half  filled  with  stringy  asbestos,  and  dried  in  a  water 
oven  at  100°  C.  to  constant  weight,  cooled  and  weighed. 
The  difference  gives  water  in  the  sample.  The  gooch  is 
then  treated  repeatedly  with  small  portions  of  gasoline, 
suction  being  applied,  and  again  dried  in  the  water  oven. 


218  Testing  Mill'  and  Its  Products. 

cooled,  and  weighed;  the  fat  in  the  sample  is  obtained 
from  the  difference  between  this  and  the  preceding 
weight.  The  gooch  is  then  carefully  heated  over  direct 
flame  until  a  light  greyish  ash  is  obtained;  this  operation 
is  preferably  done  in  a  muffle  oven  to  avoid  a  loss 
of  alkali  chlorids.  The  loss  in  weight  gives  the  casein  in 
the  sample  weighed  out,  and  the  increase  in  the  weight 
of  the  gooch  over  that  of  the  empty  gooch  with  asbestos, 
gives  the  ash  (mainly  salt)  of  the  butter.  The  salt  in  the 
ash  may  be  dissolved  out  by  hot  water,  and  the  chlorin 
content  of  the  solution  determined  by  means  of  a  stand- 
ard silver-nitrate  solution,  using  potassium  chromate  as 
an  indicator. 

269.  A  practical  method  of  estimating  the  salt  content  of 
butter.  A  method  of  estimating  the  salt  content  of  butter, 
which  is  applicable  also  outside  of  chemical  laboratories,  has 
been  worked  out  jointly  by  Messrs.  Alfred  Vivian  and  C.  L- 
Fitch.'  The  salt  of  the  butter  is  dissolved  in  hot  water,  and  a 
certain  portion  of  the  solution  when  cool  is  pipetted  off  and 
titrated  with  a  silver-nitrate  solution  prepared  by  dissolving 
one  silver-nitrate  tablet  in  50  cc.  water,  potassium  chromate 
being  used  as  an  indicator.  The  silver  nitrate  tablets  are  sold 
for  GO  cents  per  100,  which  number  is  sutficientto  make  100-150 
tests.  The  method  has  been  advertised  in  the  dairy  press  under 
the  name  of  "  Fitch's  Salt  Analysis."  Directions  for  making 
tests  by  this  method  are  furnished  with  the  apparatus  when 
this  is  bouglit.     The  price  of  a  complete  outfit  is  $4.50. 

Detection  of  Artificial  Butter. 

270.  Determination  of  the  specific  gravity  of  the  fil- 
tered butter  fat  serves  as  a  good  preliminary  test.  A 
number  of  practical  methods  for  the  detection  of  artifi- 
cial butter  have  been  proposed,  but  they  are  either  worth- 


iWis.  Experiment  Station,  XVII  Report,   pp.  98-JOl;  Hoard's  Dairy 
man,  February  15,  1901,    "  Uniform  Salting  of  Butter." 


Chemical  Analysis  of  Milk  and  Its  Products.       219 

less,  in  case  of  samples  containing  a  considerable  propor- 
tion of  natural  butter,  or  give  satisfactory  results  only  in 
the  hands  of  experts.  The  Eeichert-Wollny  method  given 
in  detail  below  is  the  standard  method  the  world  over, 
and  the  results  obtained  by  it  are  accepted  in  the  courts. 

271.  Filtering  the  butter  fat.  The  butter  to  be  exam 
ined  is  placed  in  a  small  narrow  beaker  and  kept  at  60° 
C.  for  about  two  hours.  The  clear  supernatant  fat  is 
then  filtered  through  absorbent  cotton  into  a  200  cc.  Erlen- 
meyer  flask,  taking  care  that  none  of  the  milky  lower 
portion  of  the  contents  of  the  beaker  be  poured  on  the 
filter.  In  sampling  the  butter  fat,  it  is  poured  back  and 
forth  repeatedly  from  a  small  warm  beaker  into  the 
flask,  and  the  quantity  wanted  is  then  drawn  off  with  a 
warm  pipette. 

272.  Specific  gravity.  This  is  generally  determined  at 
100°  C.  The  method  of  procedure  is  similar  to  that  de- 
scribed under  milk  (248).  The  picnometer  (capacity 
about  25  cc.)  is  filled  with  dry  filtered  butter  fat,  free 
from  air  bubbles;  the  fat  is  heated  for  30  minutes  in  a 
beaker,  the  water  in  which  is  kept  boiling.  On  cooling, 
the  weight  of  picnometer  and  fat  is  obtained,  and  by  cal- 
culation as  usual,  the  specific  gravity  of  the  fat. 

The  specific  gravity  of  pure  natural  butter  fat  at  100°  C. 
ranges  between  .8650  and  .8685,  while  artificial  butter  fat 
(i.  e.,  fat  from  other  sources  than  cows'  milk)  has  a  spe- 
cific gravity  at  100°  C.  of  below  .8610,  and  generally 
about .85. 

273.  Reichert-Wollny  method  (Fo^a^i^e  4cids).  5.75  cc. 
of  fat  are  measured  into  a  strong  250  cc.  weighed  saponi- 
fication flask,  by  means  of  a  pipette  marked  to  deliver 


220  Testing  Milk  and  Its  Products. 

this  amount,  and  the  flask  when  cool  is  weighed  again. 
10  cc.  of  95  per  cent. -alcohol  and  2  cc.  of  a  concentrated 
soda  solution  (1:1)  are  then  added  to  the  flask  which  is 
securely  stoppered  with  a  cork  stopper  tied  down  with  a 
piece  of  twine.  The  flask  is  heated  for  an  hour  on  the 
water  bath,  being  gently  rotated  from  time  to  time  in 
order  to  facilitate  the  saponification.  The  flask  is  then 
uncorked,  the  alcohol  evaporated  slowly  and  the  heating 
continued  until  the  last  traces  of  alcohol  are  gone. 

100  cc.  of  recently  boiled  distilled  water  are  now  added, 
and  the  flask  heated  on  the  water  bath  until  the  soap 
formed  is  completely  dissolved.  When  cooled  to  about 
70°  C,  40  cc.  of  dilute  sulfuric  acid  (25  cc.  cone.  H2SO4 
per  liter)  are  added  to  the  soap  solution  to  decompose 
the  soap  into  free  fatty  acids  and  glycerol.  The  flask  is 
restoppered  and  heated  until  the  insoluble  fatty  acids 
separated  out  form  a  clear  oily  layer  on  the  surface  of 
the  acid  solution  in  the  flask.  After  cooling  to  room 
temperature,  a  few  pieces  of  pumice  stone  (prepared  by 
throwing  the  pieces  at  a  white  heat  into  distilled  water 
and  keeping  them  under  water  until  used)  are  added, 
the  flask  connected  with  a  glass  condenser,  heated  slowly 
till  boiling  begins,  and  the  contents  then  distilled  at  such 
a  rate  as  will  bring  110  cc.  of  the  distillate  over  in  as 
nearly  thirty  minutes  as  possible. 

The  distillate  is  mixed  thoroughly  and  filtered  through 
a  dry  filter;  100  cc.  of  the  filtrate  are  poured  into  a  250  cc. 
beaker  and  titrated  with  a  deci-normal  barium-hydrate 
solution,  half  a  cubic  centimeter  of  phenol phtalein  solu- 
tion being  used  as  an  indicator.  A  blank  test  is  made 
in  the  same  manner  as  described,   and  the  amount  of 


Chemical  Analysis  of  Milk  and  Its  Products.       221 

alkali  solution  used  deducted  from  the  results  obtained 
with  the  samples  analyzed.  The  number  of  cubic  centi- 
meters of  barium- hydrate  solution  used  is  increased 
by  one-tenth,  and  the  so-called  Reichert  number  thus 
obtained. 

The  Eeichert  number  for  pure  butter  fat  will  ordinar- 
ily come  above  24  cc. ;  butter  fat  from  stripper  cows  will 
have  a  low  Eeichert  number.  Pure  oleomargarine  will 
have  a  Reichert  number  of  1-2  cc. ;  and  mixture  of  arti- 
ficial and  natural  butters  will  give  iutermeciiate  cumbers. 

Tests  foic  the  Detection  of  Oleomargarine  or 
Renovated  Butter. 
274.  The  boiling  test/  A  piece  of  butter  of  the  size  of 
a  small  chestnut  is  melted  in  an  ordinary  tablespoon  (or 
a  small  tin  dish)  at  a  low  heat,  stirring  with  a  splinter 
of  wood.  The  heat  is  increased  until  as  brisk  a  boil  as 
possible,  and  after  boiling  has  begun,  the  melted  mass  is 
stirred  thoroughly  two  or  three  times,  always  shortly 
before  boiling  ceases.  Oleomargarine  and  renovated 
butter  will  boil  noisily,  sputtering  like  a  mixture  of 
grease  and  water  when  boiled,  and  will  produce  but 
little  or  no  foam.  Renovated  butter  produces  usually  a 
very  small  amount  of  foam,  while  genuine  butter  boils 
with  less  noise  and  produces  an  abundance  of  foam. 

274a.  The  Waterhouse  test  for  distinguishing  oleo- 
margarine and  renovated  butter.^  Half  fill  a  100  cc. 
beaker  with  sweet  skim  milk  (or  distilled  water),  heat 


1  Patrick,  Household  tests  for  the  detection  of  oleomargarine  and  reno- 
vated butter,  Farmers'  Bulletin,  No.  131.  For  detection  and  exa  nination 
of  renovated  or  "process"  butter,  see  also  Cochran,  Jottrnl.  Fran kl.  Inst., 
1899,  p.  94 ;  Analyst,  1899,  p.  88. 

2  Farmers'  Bulletin,  No.  131,  p.  7. 


222  Testing  Milk  and  Its  Products. 

nearly  to  boiliag  and  add  5  to  lU  grams  of  butter  or 
oleomargarine.  Stir  with  a  small  wooden  stick  of  about 
the  size  of  a  match  until  the  fat  is  melted;  the  beaker  is 
then  placed  in  ice  water,  and  the  milk  (or  water)  stirred 
until  the  temperature  falls  sufficiently  for  the  fat  to 
congeal.  If  oleomargarine,  the  fat  can  now  be  easily 
collected  into  one  lump  by  means  of  the  stick,  while  if 
genuine  or  renovated  butter,  the  fat  will  granulate  and 
can  not  be  so  collected. 

D. — Cheese. 

For  method  of  sampling,  see  p.  89. 

275.  a.  Water.  Five  grams  of  cheese  cut  into  verj^ 
thin  slices  are  weighed  into  a  small  porcelain  dish  filled 
about  one- third  full  with  freshly-ignited  stringy  asbestos; 
the  dish  is  placed  in  a  water  oven  and  heated  for  ten 
hours.       The  loss  in  weight  is  taken  to  represent  water. 

276.  b.  Fat.  About  5  grams  of  cheese  are  ground 
finely  in  a  small  porcelain  mortar  with  about  twice  its 
weight  of  anhydrous  copper  sulfate,  until  the  mixture  is 
of  a  uniform  light  blue  color  and  the  cheese  evenly  dis- 
tributed throughout  the  mass.  The  mixture  is  trans- 
ferred to  a  glass  tube  of  the  kind  used  in  butter  analysis 
(263),  only  a  larger  size;  a  little  copper  sulfate  is  placed 
at  the  bottom  of  the  tube,  then  the  mixture  containing 
the  cheese,  and  on  top  of  it  a  little  extracted  absorbent 
cotton  or  ignited  stringy  asbestos;  the  tube  is  placed  in 
an  extraction  apparatus  and  extracted  with  anhydrous 
ether  for  fifteen  hours.  The  ether  is  then  distilled  off, 
the  flasks  dried  in  a  water  oven  at  100°  C.  to  constant 
weight,  cooled  and  weighed.     The  method  is  apt  to  give 


Chemical  Analysis  of  Milk  and  Its  Products.       223 

too  low  results  and,  therefore,  not  to  be  preferred  to  the 
Babcock  test  for  cheese  (102). 

277.  c.  Casein  (total  nitrogen  x  6.25).  About  2  grams 
of  cheese  are  weighed  out  on  a  watch  glass  and  trans- 
ferred to  a  Jena  nitrogen  flask,  and  the  nitrogen  in  the 
sample  determined  according  to  the  Kjeldahl  method 
(253);  the  percentage  of  nitrogen  multiplied  by  6.25 
gives  the  total  nitrogenous  components  of  the  cheese. 

278.  d.  Ash.  The  residue  from  the  water  determina- 
tion is  taken  for  the  ash;  it  is  preferably  set  fire  to,  in 
the  same  manner  as  explained  under  determination  of 
ash  in  butter  (267),  before  it  is  placed  in  the  muffie  oven 
and  incinerated.  The  increase  in  the  weight  above  that 
of  the  empty  dish + asbestos,  gives  the  amount  of  ash  in 
the  sample  weighed  out. 

279.  e.  Other  constituents.  The  sum  of  the  percent- 
ages of  water,  fat,  casein  and  ash,  subtracted  from  100, 
will  give  the  per  cent,  of  other  constituents,  organic 
acids,  milk  sugar,  etc.,  in  the  cheese. 

Detection  of  Oleomaeoarine  Cheese  (^'Filled" 
Cheese). 

280.  About  25  grams  of  finely-divided  cheese  are 
extracted  with  ether  in  a  Caldwell  extractor  or  a  paper 
extraction  cartridge;  the  ether  is  distilled  off,  and  the 
fat  dried  in  the  water  oven  until  there  is  no  further  loss 
in  weight.  5.75  cc.  of  the  clear  fat  are  then  measured 
into  a  250  cc.  saponification  flask  and  treated  according 
to  the  Eeichert-Wollny  method,  as  already  explained 
under  Detection  of  Artificial  Butter  (270).^ 


1  See  Arb.  Kais.  Ges.-Amt.,  14,  50G-598. 


224  Testinr/  Milk  and  1(8  Products. 

Tests  for  Anui/rERATioN  of  Milk  and  Cream. 

28L  The  nitric  acid  test  may  prove  useful  as  corrobora- 
tive evidence  that  a  sample  of  milk  has  been  watered 
(123).  Normal  fresh  milk  does  not  contain  nitrates, 
while  common  well-water,  particularly  on  farms  where 
precautions  to  guard  against  contamination  of  the  water 
supply  have  not  been  taken,  in  general  contains  appreci- 
able amounts  of  nitrates,  nitrites  and  ammonia  com- 
pounds, and  watered  milk  will,  therefore,  in  such  cases 
also  contain  nitrates.^  The  method  for  detection  of  small 
amounts  of  nitrates  in  milk,  as  given  by  Eichmond^  is 
as  follows:  Place  a  small  quantity  of  diphenylamin  at 
the  bottom  of  a  porcelain  dish,  and  add  to  it  about  1  cc. 
of  pure  H.^SO^  (cone);  allow  a  few  drops  of  the  milk 
serum  (obtained  by  adding  a  little  acetic  acid  to  the  milk 
and  warming)  to  flow  down  the  sides  of  the  dish  and 
over  the  surface  of  the  acid.  If  a  blue  color  developes 
in  the  course  of  ten  minutes,  though  it  may  be  faint,  it 
shows  the  presence  of  nitrates,  after  ten  minutes  a  red- 
dish-brown color  is  always  developed  from  the  action  of 
the  acid  on  the  serum.  There  should  be  no  difficulty  in 
detecting  an  addition  of  10  per  ct.  of  water  to  the  milk 
by  this  test,  if  the  water  added  contained  5  parts  of  nitric 
acid,  or  more,  per  100,000. 

Besides  by  the  methods  given  in  the  preceding  (pp. 
1(11-107),  watering  or  skimming  of  milk  may  be  detected 
by  determining  the  specific  gravity  of  a,  the  skim  milk, 
b,  the  milk  serum,  and  c,  the  whey. 


1  Uffelmann,  Deutsche  Vierteljahresschr.  f.  off.  Ges.-pfl.  15,  p. 

2  The  Analyst,  1893,  p.  272. 


Ohemical  Analysis  of  Milk  and  Its  Products.       225 

282.  a.  Specific  gravity  of  skim  milk.  The  milk  is  set 
\A  a  flat  porcelain  or  glass  dish  for  12-24  hours  in  a  cold 
room;  the  layer  of  cream  formed  is  then  skimmed  off, 
and  the  sp.  gr.  of  the  skim  milk  determined  at  60°  F. 
Skim  milk  has  a  sp.  gr.  of  .002  to  .0035  (2  to  3.5  lactom- 
eter degrees)  above  that  of  the  corresponding  whole 
milk;  a  smaller  difference  than  this  indicaies  that  the 
milk  was  skimmed.  If  both  skimming  and  watering  had 
been  practiced,  the  difference  given  above  might  be  ob- 
tained, but  the  analysis  of  the  milk  would  in  such  case 
easily  disclose  the  adulteration. 

283.  Specific  gravity  of  the  milk  serum.  To  100  cc. 
milk  2  cc.  of  20  per  ct. -acetic  acid  are  added,  and  the 
mixture  heated  in  a  covered  beaker  or  closed  flask  for 
5-10  min.  on  a  water- bath  at  55-65°  C.  After  cooling, 
the  milk  serum  is  filtered  off  and  its  sp.  gr.  determined 
at  60°  F.  In  case  of  pure  milks,  the  sp.  gr.  of  the  milk 
serum  (at  60°)  will  come  above  1.0270.  Serum  from 
normal  milks  contain  6.3  to  7.5  per  ct.  solids  and  .22 
to  .28  per  ct.  fat;  by  the  £.ddition  of  10  per  ct.  of  water, 
the  solids  in  the  serum  are  lowered  .3  to  .5  per  ct.,  and 
thesp.  gr.,  .0005.1 

c.  Specific  gravity  of  whey.  500  cc.  of  milk  are  warmed 
in  water  of  40-50°  0.  until  its  temperature  is  35°  C. ; 
one-half  cc.  of  rennet  extract  (12-15  drops)  is  added, 
and  the  milk  stirred  thoroughly.  After  allowing  the 
curd  to  solidify  for  10  minutes,  it  is  cut  and  the  whey 
filtered  off  through  several  layers  of  cheese  cloth.  The 
whey  must  be  clear;  it  is  cooled  to  15°  C.  and  its  sp.  gr. 
determined.     The  sp.  gr.  of  whey  from  normal  milk  ob- 


1  Konlg,  Menschl.  Nahrungsmittel,  II,  p.  276. 
15 


226  Testing  Milk  and  Its  Products. 

taiaed  in  the  manner  given  will  range  between  1.027 
and  1.031.  A  sp.  gr.  of  1.026  or  below  indicates  water- 
ing. An  addition  of  4  per  ct.  of  water  lowers  the  sp.  gr. 
of  the  whey  about  1  lactometer  degree.' 

284.  Detection  of  coloring  matter.  Milk  which  has 
been  watered  or  skimmed,  or  both,  is  sometimes  further 
adulterated  by  unscrupulous  milk  dealers  by  an  ad- 
dition of  a  small  quantity  of  cheese  color;  this  will 
mix  thoroughly  with  the  milk,  and,  if  added  judiciously, 
will  impart  a  rich  cream  color  to  it.  The  presence  of 
foreign  coloring  matter  in  milk  is  easily  shown  by  shak- 
ing 10  cc.  of  the  milk  with  an  equal  quantity  of  ether; 
on  standing,  a  clear  ether  solution  will  rise  to  the  surface; 
if  artificial  coloring  matter  has  been  added  to  the  milk, 
the  solution  will  be  yellow  colored,  the  intensity  of  the 
color  indicating  the  quantity  added;  natural  fresh  milk 
will  give  a  colorless  ether  solution. 

A  method  given  by  Wallace-  is  claimed  to  detect  one 
part  of  coloring  matter  in  100,000  of  milk. 

Inorganic  coloring  matter  like  chromates  and  bi-chro- 
mates  have,  although  fortunately  rarely,  been  used  to 
impart  a  rich  color  to  adulterated  milk  or  poor  cream. 
Chromates  may  be  detected  by  the  reddish  yellow  color 
produced  when  a  little  2  per  cent. -silver  nitrate  solution 
is  added  to  a  few  cubic  centimeters  of  the  milk. 

285.  Detection  of  pasteurized  milk  or  cream.  Prof. 
Storch,  of  Copenhagen,  Denmark,^  in  1898,  published  a 
simple  method  for  ascertaining  whether  milk,  cream, 
butter  or  other  dairy  products  have  been  heated  to  at 
least  176°  F.  (80°  C).  The  test  is  made  as  follows:  A 
teaspoonful  of  the  milk  is  poured  into  a  test  tube,  and 

1  Siats,  Unters.  landw.  wicht.  Stoffe,  p.  88. 

2  N.  J.  Dairy  Commissioner,  report.  1896,  p.  36. 

3  40th  report,  Copenhagen  experiment  station. 


Chemical  Analysis  of  Milk  and  Its  Products.       227 

1  drop  of  a  weak  solution  of  peroxid  of  hydrogen  (2  per 
cent.)  and  2  drops  of  a  paraphenylenediamin-solution 
(2  per  cent.)  are  added.  The  mixture  is  then  shaken; 
if  a  dark  violet  color  appears  at  once,  the  milk  has  not 
been  heated,  or  at  any  rate  not  beyond  176°  F.  If  a 
sample  of  butter  is  to  be  examined,  25  grams  are  placed 
in  a  small  beaker  and  melted  by  being  placed  in  water 
of  60°  C.  The  clear  butter  fat  is  poured  off,  and  the 
remaining  liquid  is  diluted  with  an  equal  volume  of 
water.  The  mixture  thus  obtained  is  examined  as  in 
case  of  milk. 

286.  Boiled  milk.  The  preceding  test  will  serve  to 
distinguish  between  raw  and  boiled  milk,  and  also  to 
ascertain  if  milk  has  been  adulterated  with  diluted  con- 
densed milk.  To  what  extent  such  an  adulteration  can 
be  practiced  without  being  detected  by  this  or  similar 
tests,  has  not  been  determined,  but  if  a  control  test  be 
made  at  the  same  time  with  a  sample  of  milk  of  known 
purity,  a  small  admixture  of  boiled  (or  diluted  con- 
densed) milk  can  doubtless  be  detected.^ 

287.  Gelatine  in  cream.  This  method  of  adulteration 
is  sometimes  practiced  in  the  city  cream  trade,  to  impart 
stiffness  and  an  appearance  of  richness  to  the  cream.  To 
detect  the  gelatine,  a  quantity  of  the  suspected  cream  is 
mixed  with  warm  water,  and  acetic  acid  is  added  to 
precipitate  the  casein  and  fat  (1.5  cc.  of  10  per  cent.- 
acetic  acid  per  10  cc.  of  cream  is  sufficient).  The  pre- 
cipitate is  filtered  off,  and  a  few  drops  of  a  strong  tannin 
solution  are  added  to  the  clear  filtrate.  ?ure  cream  will 
give  a  slight  precipitate,  while  in  the  presence  of  gela- 
tine a  copious  precipitate  will  come  down. 


1  See  also  Siats,  Unters.  landw.  wicht.  Stoffe,  p.  60,  and  Molkerei-Ztg. 
(Hildesheim),  1899.  p.  677. 


228  Testing  Milk  and  Its  Products. 

The  picric- acid  method  has  also  been  proposed  for  the 
detection  of  small  quantities  of  gelatine  in  cream.  ^ 

288.  Starch  in  cream.  Starch  is  mentioned  in  the  dairy 
literature  as  an  adulterant  of  milk  and  cream.  It  is 
doubtful,  however,  if  it  is  ever  used  for  this  purpose  at 
the  present  time.  In  the  case  of  ice-cream,  on  the  other 
hand,  a  small  quantity  of  corn  starch  is  often  added  to 
thicken  the  milk  used.  It  may  in  such  a  case  be  readily 
detected  by  means  of  the  iodin  reaction.  A  solution  of 
iodin  will  produce  a  deep  blue  color  in  the  presence  of 
starch;  a  small  amount  of  iodin  is  taken  up  by  the  cream 
before  the  blue  coloration  appears. 

289.  Macroscopic  impurities  (particles  of  hay,  litter, 
woolen  or  cotton  fibres,  dung,  etc.)  These  impurities 
may  be  separated  by  repeated  dilution  of  the  milk  with 
pure  distilled  water,  leaving  the  mixture  undisturbed 
for  a  couple  of  hours  each  time  before  the  liquid  is 
syphoned  off.  When  the  milk  has  been  entirely  removed 
in  this  manner,  the  residue  is  filtered  off,  dried  and 
weighed.  A  quart  of  milk  or  cream  should  not  give  any 
visible  sediment  on  standing  for  several  hours. 

Detection  of  Present atives  in  Daiey  Products. 

290.  a.  Boracic  acid  (borax,  borates,  preservaline,  etc.). 
100  cc.  of  milk  are  made  alkaline  with  a  soda  or  potash 
solution,  and  then  evaporated  to  dryness  and  incinerated. 
The  ash  is  dissolved  in  water  to  which  a  little  hydro- 
chloric acid  has  been  added,  and  the  solution  filtered. 
A  strip  01  turmeric  paper  moistened  with  the  filtrate  will 
be  colored  reddish  brown  when  dried  at  100°  C.  on  a 
watch  glass,  if  boracic  acid  is  present. 

If  a  little  alcohol  is  poured  over  the  ash  to  which  con- 
centrated sulfuric  acid  has  been  added,  and  fire  is  set  to 


1  The  Analyst,  1897,  p.  320. 


Chemical  Analysis  of  Milk  and  Its  Products.       229 

the  alcohol  after  a  little  while,  it  will  burn  with  a  yel- 
lowish green  tint,  especially  noticeable  if  the  ash  is 
stirred  with  a  glass  rod  and  when  the  flame  is  about  to 
go  out. 

291.  The  following  modification  of  the  first  test  given  is  said 
to  show  the  presence  of  only  a  thousandth  of  a  grain  of  borax 
in  a  drop  of  milk  (about  .15  per  cent. )  :^ 

Place  in  a  porcelain  dish  one  drop  of  milk  with  two  drops  of 
strong  hydrochloric  acid  and  two  drops  of  saturated  turmeric 
tincture;  dry  this  on  the  water  bath,  cool  and  add  a  drop  of 
ammonia  by  means  of  a  glass  rod.  A  slaty  blue  color  changing 
to  green  is  produced  if  .borax  is  present.- 

292.  b.  Bi-Carbonate  of  soda.  100  cc.  of  milk  to  which 
a  few  drops  of  alcohol  are  added,  are  evaporated  and 
carefully  incinerated;  the  proportion  of  carbonic  acid  in 
the  ash  as  compared  with  that  of  milk  of  known  purity 
is  determined.  If  an  apparatus  for  the  determination  of 
carbonic  acid  is  available,  like  the  Scheibler  apparatus, 
etc.,  the  per  cent,  of  carbonic  acid  per  gram  of  ash  (and 
quart  of  milk)  can  be  easily  ascertained.  Normal  milk 
ash  contains  only  a  small  amount  of  carbonic  acid  (less 
than  2  per  cent. ),  presumably  formed  from  the  citric  acid 
of  the  milk  in  the  process  of  incineration. 

The  following  qualitative  test  is  easily  made:  To  10  cc. 
of  milk  add  10  cc.  of  alcohol  and  a  little  of  a  one  per  cent, 
rosolic-acid  solution.  Pure  milk  will  give  a  brownish 
yellow  color;  milk  to  which  soda  has  been  added,  a  rose 
red  color.  A  control  experiment  with  milk  of  known 
purity  should  be  made. 

293.  c.  riuroids.  100  cc.  of  milk  are  evaporated  in  a 
platinum  or  lead  crucible,  and  incinerated;  the  ash  is 
made  strongly  acid  with  concentrated  sulfuric  acid.  If 
fluroids  are  present,  hydrofluoric  acid  will  be  generated 

1  N.  J.  Dairy  Commissioner,  report  1896,  p.  37. 

2  See  also  139, 144. 


230  Testing  Milk  and  Its  Products. 

on  gentle  heating  and  will  be  apparent  from  its  etching 
a  watch  glass  placed  over  the  crucible. ' 

294.  d.  Salicylic  acid  (salicylates,  etc.).  20  cc.  of  milk 
are  acidulated  with  sulfuric  acid  and  shaken  with  ether; 
the  ether  solution  is  evaporated,  and  the  residue  treated 
with  alcohol  and  a  little  iron-chlorid  solution;  a  deep 
violet  color  will  be  obtained  in  the  presence  of  salicylic 
acid. 

295.  e.  Formaldehyde  (a  forty-per  cent,  solution  in 
water).  A  solution  of  diphenylamin  is  made  with  water 
and  just  enough  sulfuric  acid  to  dissolve  it.  The  milk 
to  be  tested,  or  better,  the  distillate  therefrom,  is  added 
to  this  solution  and  boiled.  If  formalin  be  present,  a 
white  flocculent  precipitate  is  formed;  if  the  acid  used 
contained  nitrates,  a  green  precipitate  will  be  formed. 

The  following  method  by  Hehner  is  stated  to  show  the 
presence  of  1  part  of  formaldehyde  in  200,000  parts  of 
milk:  the  milk  is  diluted  with  an  equal  volume  of  water, 
and  strong  H.^SO^  (sp.  gr.  1.82-1.84)  is  added.  A  vio- 
let ring  is  formed  at  the  junction  of  the  two  liquids  if 
formaldehyde  is  present;  if  not,  a  slight  greenish  tinge 
will  be  seen.  The  violet  color  is  not  obtained  with  milks 
containing  over  .05  per  cent,  formaldehyde.  - 

An  adulteration  of  milk  with  formaldehyde  may  be 
readily  detected  by  the  following  method,  which  will 
show  the  presence  of  only  a  trace  of  formaldehyde  in  the 
milk.  5  cc.  of  milk  is  measured  into  a  white  porcelain 
dish,  and  a  similar  quantity  of  water  added.  10  cc.  of 
HCl  containing  a  trace  of  Fe.^Clg  is  added,  and  the 
mixture  is  heated  very  slowly.  If  formaldehyde  is  pres- 
ent, a  violet  color  will  be  formed. 

1  Chromales  in  dairy  products  may  be  readily  determined  by  the  use  of 
a  silver-nitrate  solution,  see  Molkerei  Ztg.  (Ber  in)  18i)9,  p.  603. 

2  Chem.  News,  1896,  No.  71;  Milchzeitung,  1896,  491;  1897,  40,  667;  The  An- 
alyst,  1895,  152,  154,  157;  1896,  285. 


GOVEENMENT   STAND AEDS   OF   PUEITY  FOE 
MILK   AI^D   ITS   PEODUCTS. 


a.    MILK. 

Definition.  1.  Milk  {whole  milk)  is  the  lacteal  secretion  ob- 
tained by  the  complete  milking  of  one  or  more  healthy  cows, 
properly  fed  and  kept,  excluding  that  obtained  within  fifteen 
days  before  and  five  days  after  calving. 

Standard.  Standard  milk  is  milk  containing  not  less  than 
twelve  ( 12)  per  cent,  of  total  solids  and  not  less  than  eight  and 
one  half  (8.5)  per  cent,  of  solids  not  fat,  nor  less  than  three 
and  one-quarter  (3.25)  per  cent,  of  milk  fat. 

Definitions.  2.  Blended  milk  is  milk  modified  in  its  composi- 
tion so  as  to  have  a  definite  and  stated  percentage  of  one  or 
more  of  its  constituents. 

3.  Skim  milk  is  milk  from  which  a  part  or  all  of  the  cream 
has  been  removed. 

Standard.  Standard  skim  milk  is  skim  milk  containing  not 
less  than  nine  and  one-quarter  (9.25)  per  cent,  of  milk  sohds. 

4.  Buttermilk  is  the  product  that  remains  when  butter  is 
removed  from  milk  or  cream  in  the  process  of  churning. 

5.  Pasteurized  milk  is  standard  milk  that  has  been  heated 
below  boiling  but  sufficiently  to  kill  most  of  the  active  organ- 
isms present  and  immediately  cooled  to  fifty  degrees  (50°)  Fahr. 
or  lower  to  retard  the  development  of  their  spores. 

6.  Sterilized  milk  is  standard  milk  that  has  been  heated  at 
the  temperature  of  boiling  water  or  higher  for  a  length  of  time 
sufficient  to  kill  all  organisms  present. 

7.  Condensed  milk  is  milk  from  which  a  considerable  por- 
tion of  water  has  been  evaporated. 

8.  Sweetened  Condensed  milk  is  milk  from  which  a  consider- 
able portion  of  water  has  been  evaporated  and  to  which  sugar 
(sucrose)  has  been  added. 

Standard.  Standard  condensed  milk  and  standard  sweetened 
condensed  milk  are  condensed  milk  and  sweetened  condensed 
milk,  respectively,  containing  not  less  than  twenty-eight  (28) 
per  cent  of  milk  solids,  of  which  not  less  than  one-fourth  is 
milk  fat. 

9.  Condensed  skim  milk  is  skim  milk  from  which  a  consider- 
able portion  of  water  has  been  evaporated. 

b.    MILK   FAT   OR   BUTTER   FAT. 

Definition.  1.  Milk  fat  or  butter  fat  is  the  fat  of  milk. 

Standard.  Standard  milk  fat  or  butter  fat  has  a  Eeichert- 
Meissl  number  not  less  than  twenty-four  (24)  and  a  specific 
gravity  not  less  than  0.905  (40°  C.  /40°  C. ). 

inno^  Circular  No.  10,  Office  of  the  Secretary,  U.  S.  Dept.  Agriculture,  Nov. 
1903. 


232  Testing  Milk  and  Its  Products. 

C.    CREiLM. 

Definition.  1.  Oeam  is  that  portion  of  milk,  rich  in  butter  fat, 
which  rises  to  the  surface  of  milk  on  standing,  or  is  separated 
from  it  bj'^  centrifugal  force. 

Standard.  Standard  cream  is  cream  containing  not  less 
than  eighteen  (18)  per  cent,  of  milk  fat. 

2.  Evaporated  cream  is  cream  from  which  a  considerable 
portion  of  water  has  been  evaporated. 

d.  BUTTER. 

Definition.  1.  Butter  is  the  product  obtained  by  gathering  in 
any  manner  the  fat  of  fresh  or  ripened  milk  or  cream  into  a 
mass,  which  also  contains  a  small  portion  of  the  other  milk 
constituents,  with  or  without  salt.  By  acts  of  Congress  ap- 
proved August  2d,  1886,  and  May  9th,  1902,  butter  maj'  also  con- 
tain additional  coloring  matter. 

Standard.  Standard  butter  is  butter  containing  not  less  than 
eighty-two  and  five-tenths  (82.5)  per  cent,  of  butter  fat. 

Definition.  2.  Renovated  or  process  butter  is  the  product  ob- 
tained by  melting  butter  and  reworking,  without  the  addition 
or  use  of  chemicals  or  any  substances  except  milk,  cream,  or 
salt. 

Standard.  Standard  renovated  or  process  butter  is  renovated 
or  process  butter  containing  not  more  than  sixteen  (16)  per 
cent,  of  water  and  at  least  eighty-two  and  five-tenths  (82.5)  per 
cent,  of  butter  fat. 

e.  CHEESE. 

Definitions.  1.  Cheese  is  the  solid  and  ripened  product  obtained 
by  coagulating  the  casein  of  milk  by  means  of  rennet  or  acids, 
with  or  without  the  addition  of  ripening  ferments  and  season- 
ing. By  act  of  Congress,  approved  June  6,  1896,  cheese  may 
also  contain  additional  coloring  matter. 

2.  Whole-milk  or  full-crearn  cheese  is  cheese  made  from  milk 
from  which  no  portion  of  the  fat  has  been  removed. 

3.  Cream  cheese  is  cheese  made  from  milk  and  cream,  or 
milk  containing  not  less  than  six  (6)  per  cent,  of  fat. 

Standard.  Standard  whole-milk  cheese  or  full-cream,  cheese  is 
whole-milk  or  full-cream  cheese  containing  in  the  water-free 
substance,  not  less  than  fifty  (50)  per  cent,  of  butter  fat. 

f.    MISCELLANEOUS  MILK   PRODUCTS. 

Definitions.  1.  Whey  is  the  product  remaining  after  removal 
of  fat  and  casein  from  milk  in  the  process  of  cheese  making. 

2.  Kumiss  is  mare's  or  cow's  milk,  with  or  without  the 
addition  of  sugar  (sucrose),  which  has  undergone  alcoholic 
fermentation. 


APPENDIX. 


Table  I.     Composition  of  milk  and  its  products. 


Cows'  milk. 


Colostrum  milk 

Cream 

Cream,  Cooley 

Skim  milk  (gravity). 

it  (i  u 

Skim  milk  (Centrifagal). 
Buttermilk 


Whey 


No.  of 
analyses 


793 


5,552 

2,173 

200,000 

42 

43 

203 

56 

354 


Water 


Condensed  milk, 

(no  sugar  added).., 
Condensed  milk, 

(sugar  added) 

Butter,  salted 

"      sweet  cream 

"      sour  cream 

"      unsalted 

"      World's  Fiir,  1893 

Cheese,  cream 

"       full  cream 

"       Cheddar,  green 

"       Cheddar,  cured 

World's  Fair 

Mam'th,  1893 

"       half-skim 

"       skim 

"        centrifogal  skini.... 


87 
87 
87 
86 
7 
4 
68 
73 
90, 
90 
90 
90, 
91. 
93. 
93. 


36 

64 
,676 
10 
11 
242 
350 
12 
143 


Fat. 


58.99 

25.61 

11.95 

12.93 

13.08 

13.07 

11.5 

36.33 

38.00 

36.84 

34.38 

32.06 
39.79 
46.00 
50.5 


pr.  ct. 

3. 

3.40 

3.90 

4.20 

3.90 

3.59 

22.66 

17.60 

.87 

.32 

.10 

1.09 

.27 

.32 

.27 

12.42 


10.35 

84.2' 
84.53 
84.26 
85.24 
84.70 
40.71 
30.25 
33.83 
32.71 


Casein 

and 

alb 'men 


pr.  ct. 

3.55 
3.50 
3.20 
3.51  = 
3.40 
17.64 
3.76 

3*.26 


Milk 
sugar 


pr.  ct. 

4.88 
4.6(j 
5.10 


3.55 
4.03 


81 


11.92 


23.92 

11.65 

1.2 


4.75 
2.67 
4.23 

4. 74 


5.25 
4.04 


4.79 
5. 

14.49 

50.06 


Ash. 


pr  ct. 

.71 
.75 
.70 

^71 
.75 

1.56 
.53 
.62 
.7 


Auihority. 


11.79 
1.26 
.61  I     .68 
.81 
1.57 
.95 


18.84 
25.35 
23.72 
26.38 


34.43  28.00 


29.67 
34.06 
43.1 


.65 

80 

2.18 

2.19 

2.58 
1.25 
1.19 
.12 
2.7 
3.10 
4.97 


1.02 
1.43 

5.61 
2.95|  3.58 


5.51 


Konig.s 
Fleischmann. 
Van  Slyke. 
Holland . « 
Richmond. 
Konig.^ 
(t 

Holland. « 
Konig.5 
Holland.« 
Van  Slyke. 
Konig.5 
Holland.« 
K6nig.5 
Van  Slyke. 

Konig.s 


Woll. 
Konig. 


Woll. 

Farrington. 

Konig.s 

Van  Slyke. 
Drew. 

Shutt. 
Konig  .5 


4.73 
4.87 
5.2  Storch. 


1  70  per  cent,  of  this  amount  is  albumen. 

2  Forty-two  analyses. 

3  Eight  analyses. 


4  13.60  percent,  albumen. 

5  Mostly  European  samples. 

6  Massachusetts'  samples. 


234 


Testing  Milk  and  Its  Products. 


s 

a 
*5 


u 

rj 

T3 

e 

s 

•o 
e 

(0 

5 


1  i 

1    5 

Full  cream,  30  pr.ct.  fat. 
Halfskim,  15  pr.ct.  fat. 
Skim,  from  skim  milk. 

35  p  c.  total  sol.  to  be  fat. 

1 

bO 

M 

Ceo 

pq 

1 

? 

IS 

g 

i 

si 

HO 

o      :           :co 

1  i   \^ 

M 

1 

"o      :          :  lO              lo          i>- 

^        •              -co                    CCCCCOCOCCCO 

^     :         ; 

CO 

coco 

5i 

r — 1 

c:  rs 

s4 
SI 

:      cc-M-M-i  — 

:           :  •"- 

i  i§     li 

3    £s      di 

< 

1 

< 

J. 

J. 

J 

c 
c: 
c 

;  5 

;  t> 

;    it 

a 

;2 

'c 

X 

C 

:  H« 

:  S 

:  >i 

:  ci 

3 

Appendix. 


235 


."SS 


.   a 


^^  a 


ftS 

g 

00 

?3^ 

^ 

s 

r«  O 

XI 

•3 

)er  ct.  f 
le-half 
t.  lat. 
le-fourt 
t.  fat. 
im'd,  b 

EtH     O     O     c» 


CO-    :" 


i  «  Vl 


a-s 


"03  0  Q  1^    .CO 


I — I      lO       o 

•      •      •        00 
OQ0  05 


»0  ^S 


I — iiO 
lO      • 


a 
O 


.23 
^  9 

CO  JJ 


03 

03  P 


:  aJ 

:  Cl 

•  :3 

^   r^     :  03  -M 

CO  c3-tf  t>.  W) 


lOQO 
CO<M* 


CO  '^    C\|    CO 


o  c  o  o  o  o  o 

G^  CO  <M  <M  Ol  'M*  <m" 


I — lO  ^      lO 

"^.co-'^i^i 

1— J      OQ 


ft, 


Scg  g'^  § 


.3   O  ra  t>  ^  03    ^ 

'3  o;a  S  2X3 


o  o 


^     ^3 


.22  I  ^ 

'"'  '^3  <1^  ct  CD 

^  H  2  S  ^ 

G^  2  o  ^ 


> 
v 

O) 

II 


o 

s 

-u  t/j  oQ  t: 
fl  n  i>  S 


^.  g.3  CO 

-5  «  ^ 
1  o  o  fl 

■^  O  y  G 
•  O 


O.^ 


236 


Testing  fMiR-  and  Its  Products. 


Table  III.     Quevenne  lactometer  degrees  corresponding  to 
N.  Y.  Board  of  Health  degrees.     (See  p.  97. ) 


Bd.  of   Health 

Quevenne 

Bd.  of  Health 

Quevenne 

Bd.  of  Health 

Quevenne 

degrees. 

scale. 

degrees. 

scale. 

degrees. 

scale. 

60 

17.4 

81 

23.5 

101 

29.3 

61 

17.7 

82 

23.8 

102 

29.6 

62 

18.0 

83 

24.1 

103 

29.9 

63 

18.3 

84 

24.4 

104 

30.2 

64 

18.6 

8Si 

24.6 

105 

30.5 

65 

18.8 

86 

24.9 

106 

30.7 

66 

19.1 

87 

25.2 

107 

31.0 

67 

19.4 

88 

25.5 

108 

31.3 

68 

19.7 

89 

25.8 

109 

31.6 

69 

20.0 

90 

26.1 

110 

31.9 

70 

20.3 

91 

26.4 

111 

32.2 

71 

20.6 

92 

26.7 

112 

32.5 

72 

20.9 

93 

27.0 

113 

32.8 

73 

21.2 

94 

27.3 

114 

33.1 

74 

21.5 

95 

27.6 

115 

33.4 

75 

21.7 

96 

27.8 

116 

33.6 

76 

22.0 

97 

28.1 

117 

33.9 

77 

22  3 

98 

28.4 

118 

34.2 

78 

22.6 

99 

28.7 

119 

34.5 

79 

22.9 

100 

29.0 

120 

34.8 

80 

23.2 

Table  IV.    Value  of 


100  s— 100 


.0369. 


s 

. 

^^,  ^ 

Sp.gr.  (8)  = 

0.0000 

0.0001 

0.0002 

0.0003 

0.0004 

0.0005 

0.0006 

0.0007 

0.0008 

0.0009 

1.019 

1.864 

1.874 

1.884 

1.894 

1.903 

1.913 

1.922 

1.932 

1.941 

1.951 

1.020 

1.961 

1.970 

1.980 

1.990 

1.999 

2.009 

2.018 

2.028 

2.038 

2.047 

1.021 

2.057 

2.0G6 

2.076 

2.086 

2.095 

2.105 

2.114 

2.124 

2.133 

2.143 

1.022 

2.153 

2.162 

2.172 

2.181 

2.191 

2.200 

2.210 

2.220 

2.229 

2.239 

1.023 

2.249 

2.258 

2.267 

2.277 

2.286 

2.296 

2.306 

2.315 

2.325 

2.334 

1.024 

2.344 

2.353 

2.363 

2.372 

2.382 

2.391 

2.401 

2.410 

2.420 

2.430 

1.025 

2.439 

2.449 

2.458 

2.468 

2.477 

2.487 

2.496 

2.506 

2.515 

2.525 

1.026 

2.534 

2.544 

2.553 

2.563 

2.573 

2.582 

2.591 

2.601 

2.610 

2.620 

1.027 

2.629 

2.638 

2.648 

2.657 

2.667 

2.676 

2.686 

2.695 

2.705 

2.714 

1.028 

2.724 

2.733 

2.743 

2.752 

2.762 

2.771 

2.781 

2.790 

2.799 

2.809 

1.029 

2.818 

2.828 

2.837 

2.847 

2.856 

2.865 

2.875 

2.884 

2.893 

2.903 

1.030 

2.913 

2.922 

2.931 

2.941 

2.9.51 

2.960 

2.969 

2.979 

2.988 

2.997 

1.031 

3.007 

3.016 

3.026 

3.035 

3.044 

3.054 

3.063 

3.072 

3.082 

3.091 

1.032 

3.101 

3.110 

3.120 

3.129 

3.138 

3.148 

3.157 

3.106 

3.176 

3.185 

1.033 

3.195 

3.204 

3.213 

3.223 

3.232 

3.241 

3.251 

3.260 

3.269 

3.279 

1.034 

3.288 

3.298 

3.307 

3.316 

3.326 

3.335 

3.344 

3.354 

3.363 

3.372 

1.035 

3.382 

3.391 

3.400 

3.410 

3.419 

3.428 

3.438 

3.447 

3.456 

3.466 

1.030 

3.475 

3.484 

3.494 

3.503 

3.512 

3.521 

3.531 

3.540 

3.549 

3.559 

(See  directions  for  use,  p.  10") 


Appendix:  237 

Table  Vo    Correction-table  for  specific  gravity  of  milk. 


as 

Tempciutu 

re  of  milk  (in  degrees  Fahrenheit). 

51 

52 

53 

54 

55 

53 

57 

^53 

59 

60 

20 

19.3 

19.4 

19.4 

19.5 

19.6 

19.7 

19.8 

19.9 

19.9 

20.0 

21 

20.3 

20.3 

20.4 

20.5 

20.6 

20.7 

20.8 

20.0 

20.9 

21.0 

22 

21.3 

21.3 

21.4 

21.5 

21.6 

21.7 

21.8 

21.9 

21.9 

22.0 

23 

22.3 

22.3 

22.4 

22.5 

22.6 

22.7 

22.8 

22.8 

22.9 

23.0 

24 

23.3 

23.3 

23.4 

23.5 

2?.  6 

23!6 

23.7 

23.8 

23.9 

24.0 

25 

94  2 

24.3 

24.4 

24.5 

24.6 

24.6 

24.7 

24.8 

24.9 

25.0                  . 
:'6.-0                 \ 

26 

25  .'2 

25.2 

2.5.3 

2.5.4 

2.5.5 

25.6 

25.7 

25.8 

25.9 

27 

26.2 

26.2 

26.3 

26.4 

26.5 

26.6 

26.7 

26.8 

26.9 

1^7.0 

28 

27.1 

27.2 

27.3 

27.4 

27.5 

27.6 

27.7 

27.8 

27.9 

28.0 

29 

28.1 

28.2 

28.3 

28.4 

28.5 

28.6 

28.7 

2-^.8 

28.9 

29.0 

30 

29.1 

29.1 

29.2 

29.3 

29.4 

29.6 

29.7 

20.8 

29.9 

30.0 

31 

30.0 

30.1 

30.2 

30.3 

30.4 

30.5 

30.6 

m 

30.9 

31.0 

32 

31.0 

31.1 

31.2 

31.3 

31.4 

31.5 

31.6 

31.9 

32.0 

33 

31.9 

32.0 

32.1 

32  .'3 

3'i.4 

32.5 

32.6 

32.7 

32.9 

33.0 

34 

32.9 

33.0 

33.1 

33.2 

33.3 

33.5 

33.6 

33.7 

33.9 

34.0 

35 

33.8 

33.9 

34.0 

34.2 

34.3 

34.5 

34.6 

34.7 

34.9 

35.0 

61 

62 

03 

64 

65 

06 

67 

68 

69 

V 

• 

1|^ 

^ 

20 

20.1 

20.2 

20.2 

20.3 

20.4 

20.5 

20.6 

20.7 

'20.9 

21.0.1,0 

21 

21.1 

21.2 

21.3 

21.4 

21.5 

21.6 

21.7 

21.8 

22.0 

22.1-1' 1 

22 

22  1 

22  2 

22.3 

23.4 

22.5 

22.6 

22.7 

22.8 

23.0 

23.1-1'^ 

23 

23 '.1 

23:2 

23.3 

23.4 

23.5 

23.6 

23.7 

23.8 

24.0 

24.1-2.* 

24 

24.1 

24.2 

24.3 

24.4 

24.5 

24.6 

24.7 

24.9 

25.0 

25.1-iV^ 

25 

25.1 

25.2 

25.3 

25.4 

25.5 

25.6 

25.7 

25.9 

26.0 

26.1-^  4 

26 

26.1 

26.2 

26.3 

26.5 

26.6 

26.7 

26.8 

27.0 

27.1 

27.2  ^ii 

27 

27.1 

27.3 

27.4 

27.5 

27.6 

2Z.7 

27.8 

28.0 

28.1 

2S.2-  t7 

28 

28.1 

28.3 

28.4 

28.5 

28.6 

28.7 

28.8 

29.0 

29.1 

29.2a  >• 

29 

29.1 

29.3 

29.4 

29.5 

29.6- 

29,7 

29.9 

30.1 

30.2 

30.3-2.f 

30 

30.1 

30.3 

30.4 

30.5 

30.7 

30.8 

30.9 

31.1 

31.2 

31.3.3^ 

31 

31.2 

31.3 

31.4 

31.5- 

31.7 

31.8 

31.9 

32.1 

32.2 

32.4-.?  / 

32 

32.2 

32.3 

32.5 

32.6 

32.7 

32.9 

33.0 

33. L 

33.3 

33.4     'i 

33 

33.2 

33.3 

33.5 

33.6 

33.8 

33.9 

34.0 

34.2 

34.3 

34.5-3^^ 

34 

34.2 

34.3 

34.5 

34.6 

34.8 

34.9 

35.0 

35.2 

35.3 

35.5-3V 

35 

35.2 

35.3 

35.5 

35.6 

35.8 

35.9 

36.1 

36.2 

36.4 

36.5    ^^ 

Directions.— Bring  the  temperature  of  the  milli  to  within  10°  of 
60°  F.  Talie  the  reading  of  the  lactometer  and  that  of  the  temperature  of 
the  milk;  find  the  former  in  the  first  yertical  column  of  the  table  and  the 
latter  in  the  first  horizontal  row  of  figures;  the  figure  where  the  horizontal 
and  vertical  columns  meet  is  the  corrected  lactometer  reading;  e.g.,  ob- 
served, 31.0  at  67°  F. ;  corrected  reading,  31.9. 


238 


Testing  Milk  and  Its  Products. 


Table  VI.  Per  cent,  of  salids  not  fat,  corresponding  to  0  to 
6  per  cent,  of  fat,  and  lactometer  readings  of  26  to 

36.     (See  directions  for  use,  p.  100. ) 


o 

Lactometer  readings  at  60°  F. 

a  ^ 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 

36 

0 

6.50 

6.75 

7.00 

7.25 

7.50 

7.75 

8.00 

8.2.5 

8.50 

8.75 

9.00 

0 

0.1 

6.52 

6.77 

7.02 

7.27 

7.5:: 

/.77 

8.02 

8.27 

8.52 

8.77 

9.02 

0.1 

0.2 

6.54 

6.79 

7.04 

7.29 

7.54 

7.79 

8.04 

8.29 

8.54 

8.79 

9.04 

0.2 

0.3 

6.56 

5.81 

7.06 

7.31 

7.56 

7.81 

8.06 

8.31 

8.56 

8.81 

9.06 

0.3 

0.4 

6.58 

6.83 

7.08 

7.33 

7.58 

7.83 

8.08 

8.33 

8.58 

8.83 

9.08 

0.4 

0.5 

6.60 

6.85 

7.10 

7.35 

7.60 

7.85 

8;» 

8.35 

8.60 

8.85 

9.10 

0.5 

0.6 

6.62 

6.87 

7.12 

7.37 

7.62 

7.87 

8.12 

8.37 

8.62 

8.87 

9.12 

0.6 

0.7 

6.64 

6.89 

7.14 

7.39 

7.64 

7.89 

8.14 

8.39 

8.64 

8.89 

9.14 

0.7 

0.8 

6.66 

6.91 

7.16 

7.41 

7.66 

7.91 

8.16 

8.41 

8.66 

8.91 

9.16 

0.8 

0.9 

6.68 

6.93 

7.18 

7.43 

7.68 

7.93 

8.18 

8.43 

8.68 

8.93 

9.18 

0.9 

1.0 

6.70 

6.95 

7.20 

7.45 

7.70 

7.95 

8.20 

8.45 

8.70 

8.95 

9.20 

1.0 

1.1 

6.72 

6.97 

7.22 

7.47 

7.72 

7.97 

8.22 

8.47 

8.72 

8.97 

9.22 

1.1 

1.2 

6.74 

6.99 

7.24 

7.49 

7.74 

7.99 

8.24 

8.49 

8.74 

8.99 

9.24 

1.2 

1.3 

6.76 

7.01 

7.26 

7.51 

7.76 

8.01 

8.26 

8.51 

8.76 

9.01 

9.26 

1.3 

1.4 

6.78 

7.03 

7.28 

7.53 

7.78 

8.03 

8.28 

8.53 

8.78 

9.03 

9.28 

1.4 

1.5 

6.80 

7.05 

7.30 

7.55 

7.80 

8.05 

8.30 

8.55 

8.80 

9.05 

9.30 

1.5 

1.6 

6.82 

7.07 

7.32 

7.57 

7.82 

8.07 

8.32 

8.57 

8.82 

9.07 

9.32 

l.G 

1.7 

6.84 

7.09 

7.34 

7.59 

7.84 

8.09 

8.34 

8.59 

8.84 

9.09 

9.34 

1.7 

1.8 

6.86 

7.11 

7.36 

7.61 

7.86 

8.11 

8.36 

8.61 

8.86 

9.11 

9.37 

1.8 

1.9 

6.88 

7.13 

7.38 

7.63 

7.88 

8.13 

8.38 

8.63 

8.88 

9.13 

9.39 

1.9 

2.0 

6.90 

7.15 

7.40 

7.65 

7.90 

8.15 

8.40 

8.66 

8.91 

9.16 

9.41 

2.0 

2.1 

6.92 

7.17 

7.42 

7.67 

7.92 

8.17 

8.42 

8.68 

8.93 

9.18 

9.43 

2.1 

2.2 

6.94 

7.19 

7.44 

7.69 

7.14 

3.19 

8.44 

8.70 

8.95 

9.20 

9.45 

2.2 

2.3 

6.96 

7.21 

7.46 

7.71 

7.96 

S.121 

8.46 

8.72 

8.97 

9.22 

9.47 

2.3 

2.4 

6.98 

7.23 

7.48 

7.73 

7.98 

8.23 

8.48 

8.74 

8.90 

9.24 

9.49 

2.4 

2.5 

7.00 

7.25 

7.50 

7.75 

8.00 

8.25 

8.50 

8.76 

9.01 

9.26 

9.51 

2.5 

2.6 

7.0-2 

7.27 

7.52 

7.77 

8.02 

8.27 

8.52 

8,78 

9.03 

9.28 

9.53 

2.6 

2.7 

7.04 

7.29 

7.54 

7.79 

8.04 

8.29 

8.54 

8.80 

9.05 

0.30 

9.55 

2.7 

2.8 

7.06 

7.31 

7.56 

7.81 

8.06 

8.31 

8.57 

8.82 

9.07 

9.32 

9.57 

2.8 

2.9 

7.08 

7.33 

7.58 

7.83 

8.08 

8.33 

8.59 

8.84 

9.09 

9.34 

9.50 

2.9 

Appendix.  239 

Table  VI.    Per  cent,  of  solids  not  fat  (Continued). 


c^ 

Lactometer  Readings  at  60°  F. 

q3  o 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 

86 

i§ 

3.0 

7.10 

7.35 

7.60 

7.85 

8.10 

8.36 

8.61 

8.86 

9.11 

9.36 

9.61 

3.0 

3.1 

7.12 

7.37 

7.62 

7.87 

8.13 

8.38 

8.63 

8.88 

9.13 

9.38 

9.64 

3.1 

3.2 

7.14 

7.35 

7.64 

7.89 

S.15 

8.40 

8.65 

8.90 

9.15 

9.41 

9.66 

3.2 

8.3 

7.16 

7.41 

7.60 

7.92 

8.17 

8.42 

8.67 

8.92 

9.18 

9.43 

9.68 

3.3 

3.4 

7.18 

7.43 

7.69 

7.94 

8.19 

8.44 

8.69 

8.94 

9.20 

9.45 

9.70 

3.4 

3.5 

7.20 

7.45 

7.71 

7.96 

8.21 

8:46 

8.71 

8.96 

9.22 

9.47 

9.72 

3.5 

3.6 

7.22 

7.48 

7.73 

7.98 

8.23 

8.48 

8.73 

8.98 

9.24 

9.49 

9.74 

3.6 

3.7 

7.24 

7.50 

7.75 

8.00 

8.25 

8.50 

8.75 

OjOO 

9.26 

9.51 

9.70 

3.7 

3.8 

7.26 

7.52 

7.77 

8.02 

8.27 

8;52 

8.77 

9.02 

9.28 

9.53 

9.78 

3.8 

3.9 

7.28 

7.54 

7.7i/ 

8.04 

8.29 

8.54 

8.79 

9.04 

9.30 

9.55 

9.80 

3.9 

4.0 

7.30 

7.56 

7.81 

8.06 

8.31 

8.56 

8.81 

9.06 

9.32 

9.57 

9.83 

4.0 

4.1 

7.32 

7.58 

7.83 

8. OS 

8.3;-! 

8.58 

8.83 

9.08 

9.34 

9.59 

9.85 

4.1 

4.2 

7.34 

7.60 

7.85 
7.87 

8.10 

S.i}5 

8.6Q 

.^.85 

9.11 

9.30 

9.62 

9.87 

4.2 

4.3 

7.36 

7.62 

8.l:i 

8.37 

8.62 

8.88 

9.1^ 

9*38 

9.64 

9.89 

4.3 

4.4 

7.38 

7.64 

7.89 

8.14 

8.39 

8.64 

8.90 

9.15" 

9.40 

9.66 

9.91 

4.4 

4.5 

7.40 

7.66 

7.91 

8.16 

8.41 

8.66 

8.92 

9.17 

9.42 

9.08 

9.93 

4.5 

4.6 

7.43 

7.68 

7.93 

8.18 

8.43 

8.68 

8.94 

9.19 

9.44 

9.70 

9.95 

4.6 

4.7 

7.45 

7.70 

7.95 

8.20 

S.45 

8.70 

8.96 

9.21 

9.46 

9.72 

9.97 

4.7 

4.8 

7.47 

7.72 

7.97 

8.22 

8.47 

8.7^ 

8..  98 

9.23 

9.48 

9.74 

9.99 

4.8 

4.9 

7.49 

7.74 

7.99 

8.24 

8.49 

8.74 

/.OO 

9.25 

9.50 

9.70 

10.01 

4.9 

5.0 

7.51 

7.76 

8.01 

8.26 

8.51 

8.76 

9.02 

9.27 

9.52 

9.78 

10.03 

5.0 

5.1 

7.53 

7.78 

8.03 

8.28 

8.53 

8.19 

9.04 

9.29 

9.54 

9.80 

10.05 

5.1 

5.2 

7.55 

7.80 

8.05 

8.30 

8.55 

8.§1 

9.06 

9.31 

9.50 

9.82 

10.07 

5.2 

5.3 

7.57 

7.82 

8.07 

8.32 

8.57 

8.83 

9.08 

9.33 

9.58 

9.84 

10.09 

5.3 

5.4 

7.59 

7.84 

8.09 

8.34 

• 

8.60 

8.85 

9.10 

9.36 

9.61 

9.86 

10.^11 

5.4 

5.5 

7.01 

7.86 

8.11 

8.36 

8.62 

S.87 

9.12 

9.38 

9.63 

9.88 

10.13 

5.5 

5.6 

7.63 

7.88 

3.13 

8 .  39 

8.64  8.           .5| 

9.40 

9.6o 

9.90 

10.15 

5.6 

5.7 

7.65 

7.90 

S.lo 

8.41 

8.66 

S.yi 

3.17 

9.42 

9.67 

9.92 

10.17 

5.7 

5.8 

7.67 

7.92 

8.17 

8.43 

8.68 

8.94 

9.19 

9.44 

9.69 

9.94 

10.19 

5.8 

5.9 

7.69 

7.94 

).20 

8.45 

8.70 

8.96 

9.21 

9.46 

9.71 

9.96 

10.22 

5.9 

6.0 

7.71 

7.96 

8.22 

8.47 

8.72 

8.98 

d.2?> 

9.48 

9.73 

9.98 

10.2 

6.0 

240  Testing  Milk  and  Its  Products. 

Directions  for  Use  of  Tables  VII,  VIII,  IX,  and  XI. 

TABLES  VII,  and  Vlli.  Find  the  test  of  the  milk  in  table  VII  or 
of  cream  in  table  VIII;  the  first  or  last  horizontal  row  of  fig- 
ures, the  amounts  of  fat  in  ten  thousand,  thousands,  hundreds, 
tens,  and  units  of  pounds  of  milk  are  then  given  in  this  verti- 
cal column.  By  adding  the  corresponding  figures  for  any  given 
quantity  of  milk  or  of  cream,  the  total  quantity  of  butter  fat 
contained  therein  is  obtained. 

Example:  How  many  pounds  of  fat  Is  contained  in  8925  lbs.  of  milk 
testing  3.t).5  per  cent.?  On  p.  242,  second  column  the  lest  3.63  is  loui:d,  and 
by  going  downward  in  this  column  we  liave : 

8000  lbs 292.    lbs. 

900  lbs 32.9  lbs. 

20  lbs 7  lbs. 

5  lbs 2  lbs. 

8'.t25  lbs.  of  milk.  325.8  lbs.  of  fat. 

8925  lbs.  of  milk  testing  3.65  per  cent.,  therefore,  contains  325.8  lbs.  of 
butter  fat. 

TABLE  IX.    The  price  per  pound  is  given  in  the  outside  vertical 

columns,  and  the  weight  of  butter  fat  in  the  upper  and  lower 

horizontal  row  of  figures.     The  corresponding  tens  of  pounds 

are  found  by  moving  the  decimal  point  one  place  to  the  left, 

the  units,  by  moving  it  two,  and  the  tenths  of  a  pound,  by 

moving  it  three  places  to  the  left.    The  use  of  the  table  is, 

otherwise,  as  explained  above. 

Example:  How  much  money  is  due  for  325.8  lbs.  of  butter  fat  at  15>^ 
cents  per  pound?  lu  the  horizontal  row  of  figures  beginning  with  15>^  on 
p.  217,  we  find : 

300      lbs $46.50 

20     lbs 3.10 

5      lbs 77 

.8  lbs 12 

325.8  lbs.  $50.49 

826.8  Iba.  of  butter  fat  at  15>^  cents  per  pound,  therefore,  is  worth  $50.49. 

TABLE  XI.  Find  the  test  of  milk  in  the  upper  or  lower  hori- 
zontal row  of  figures.  The  amounts  of  butter  likely  to  be  made 
from  ten  thousand,  thousands,  hundreds,  tens,  and  units  of 
pounds  of  milk  are  then  given  in  this  vertical  column.  The  use 
of  the  table  is,  otherwise,  as  explained  above  in  case  of  table  VII. 

Example:  How  much  butter  will  584.5  lbs.  of  milk  testing  3.8  per  cent, 
he  apt  to  make  under  good  creamery  conditions?  In  the  column  headed 
3.8,  we  find : 

5000  lbs 209.0  lbs. 

800  lbs 33.4  lbs. 

40  lbs 1.7  lbs. 

6  lbs 2  lbs. 

5845  lbs.  244.3  lbs. 

5845  lbs.  of  milk  test'  ng  3.8  per  cent,  of  fat  will  make  about  244.3  Ibi.  of 
butter,  under  conditious  similar  to  those  explained  on  pp.  184-188. 


Appendix. 


241 


Table  VII.     Pounds  of  fat  in  I  to  10,000  lbs.  of  milk,  testing  3.0 
to  5.35  per  cent.     (See  directions  for  use,  p.  240.) 


3.00 

3.05 

3.10 

3.15 

3.20 

3.25 

3.30 

3.35 

3.40  3.45 

3.50 

3.55 

t 

Milk 

'" 

Milk 

lbs. 

lbs. 

10,000 

300 

305 

310 

315 

320 

325 

330 

335 

340 

345 

350 

355 

10,000 

9,000 

270 

275 

279 

284 

289 

293 

297 

302 

306 

311 

315 

320 

9,000 

8,000 

240 

244 

248 

252 

256 

260 

264 

268 

272 

276 

280 

284 

8,000 

7,000 

210 

214 

217 

221 

224 

228 

231 

235 

238 

242 

245 

249 

7,000 

6,000 

ISO 

183 

186 

189 

192 

195 

198 

201 

204 

207 

210 

213 

6,000 

5,000 

150 

153 

155 

158 

160 

163 

165 

168 

170 

173 

175 

178 

5,000 

4,000 

120 

122 

124 

126 

128 

130 

132 

134 

136 

138 

140 

142 

4,000 

3,000 

90.0 

91.5 

93.0 

94.5 

96.0 

97.5 

99.0 

101 

102 

104 

105 

107 

3,000 

2,000 

60.0 

61.0 

62.0 

63.0 

64.0 

65.0 

66.0 

67.0 

68.0 

69.0 

70.0 

71.0 

2,000 

1,000 

30.0 

30.5 

31.0 

31.5 

32.0 

32.5 

33.0 

33.5 

34.0 

34.5 

35.0 

35.5 

1,000 

900 

27.0 

27.5 

27.9 

28.4 

28.8 

29.3 

29.7 

30.2 

30.6 

31.1 

31.5 

32.0 

900 

800 

24.0 

24.4 

24.8 

25.2 

25.7 

26.0 

26.4 

26.8 

27.2 

27.6 

28.0 

28.4 

800 

700 

21.0 

21.1 

21.7 

22.1 

22.4 

22.8 

23.1 

23.5 

23.8 

24.2 

24.5 

24.9 

700 

600 

18.0 

18.3 

18.6 

18.9 

19.2 

19.5 

19.8 

20.1 

20.4 

20.7 

2].0 

21.3 

600 

500 

15.0 

15.3 

15.5 

15.8 

IG.O 

16.3 

16.5 

16.8 

17.0 

17.3 

17.5 

17.8 

500 

400 

12.0 

12  '^ 

12.4 

12.6 

12.8 

13.0 

13.2 

13.4 

13.6 

13.8 

14.0 

14.2 

400 

300 

9.0 

9.2 

9.3 

9.5 

9.6 

9.8 

9.9 

10.1 

10.2 

10.4 

10.5 

10.7 

300 

200 

6.0 

6.1 

6.2 

6.3 

6.4 

6.5 

6.6 

6.7 

6.8 

6.9 

7.0 

7.1 

200 

100 

3.0 

3.1 

3.1 

3.2 

3.2 

3.3 

3.3 

3.4 

3.4 

3.5 

3.5 

3.6 

100 

90 

2.7 

2.8 

2.8 

2.8 

2.9 

2.9 

3.0 

3.0 

3.1 

3.1 

3.2 

3.2 

90 

80 

2.4 

2.4 

2.5 

2.5 

2.6 

2.6 

2.6 

2.7 

2.7 

2.8 

2.8 

2.8 

80 

70 

2.] 

2.1 

2.2 

2.2 

2.2 

2.3 

2.3 

2.3 

2.4 

2.4 

2.5 

2.5 

70 

60 

1.8 

1.8 

1.9 

1.9 

1.9 

2.0 

2.0 

2.0 

2.0 

2.1 

2.1 

2.1 

60 

50 

1.5 

1.5 

1.6 

1.6 

1.6 

1.6 

1.7 

1.7 

1.7 

1.7 

1.8 

1.8 

50 

40 

1.2 

1.2 

1.2 

1.3 

1.3 

1.3 

1.3 

1.3 

1.4 

1.4 

1.4 

1.4 

40 

30 

.9 

.9 

.9 

.9 

1.0 

1.0 

1.0 

1.0 

1.0 

1.0 

1.1 

1.1 

30 

20 

.6 

.6 

.6 

.6 

.6 

.7 

.7 

.7 

.7 

.7 

.7 

.7 

20 

10 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.4 

.4 

10 

9 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

9 

8 

.2 

.2 

.2 

-  .3 

:3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

8 

7 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

7 

6 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

6 

5 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

5 

4 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

4 

3 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

3 

2 

1 

.1 

.1 

.1 

.1 

.1 

1 

.1 

.1 

.1 

.1 

.1 

.1 

2 

1 

1 

3.00 

3.05 

3.10 

3.15 

3.20 

3.25 

3.30 

3.35 

3.40 

3.45 

3.50 

3.55 

i 

16 


242  Testing  Milk  and  Its  Products. 

Table  VII.    Pounds  of  fat  in  i  to  10,000  lbs.  of  milk  ( Continued). 


3.60 

3.65 

3.70 

3.75 

3.80 

3.85 

3.90 

3.95 

4.00 

4.05 

4.10 

4.15 

Milk 

Milk 

lbs. 

lbs. 

10,000 

300 

365 

370 

375 

380 

.385 

390 

395 

400 

405 

410 

415 

10,000 

9,000 

324 

329 

333 

338 

342 

347 

351 

356 

360 

365 

369 

374 

9,000 

8,000 

28S 

292 

296 

300 

304 

308 

312 

316 

320 

324 

328 

332 

8,000 

7.000 

252 

256 

259 

263 

266 

270 

273 

277 

280 

284 

287 

291 

7,000 

6,000 
5,000 

216 

219 

222 

225 

228 

231 

234 

237 

240 

243 

246 

249 

6,000 

180 

183 

185 

188 

190 

193 

195 

198 

200 

203 

205 

208 

5,000 

4,000 

144 

146 

148 

150 

1.-.2 

154 

156 

158 

160 

162 

164 

166 

4,000 

3,000 

108 

110 

111 

113 

114 

116 

117 

119 

120 

122 

123 

125 

3,000 

2,000 

72.0 

73.0 

74.0 

75.0 

76.0 

77.0 

78.0 

79.0 

80.0 

81.0 

82.0 

83.0 

2,000 

1,000 

36.0 

36.5 

37.0 

37.5 

38.0 

38.5 

39.0 

39.5 

40.0 

40.5 

41.0 

41.5 

1,000 

900 

32.4 

32.9 

33.3 

33.8 

34.2 

34.7 

35.1 

35.6 

36.0 

36.5 

36.9 

37.4 

900 

800 

28.8 

29.2 

29.6 

30.0 

30.4 

30.8 

31.2 

31.6 

32.0 

32.4 

32.8 

33.2 

800 

700 

25.2 

25.6 

25.9 

26.3 

26.6 

27.0 

27.3 

27.7 

28.0 

28.4 

28.7i29.1 

700 

GOO 

21.6 

21.9 

22.2 

22.5 

22.8 

23.1 

23.4 

23.7 

24.0 

24.3 

24.6  24.9 

600 

500 

18.0 

18.3 

18.5 

18.8 

19.0 

19.3 

19.5 

19.8 

20.0 

20.3 

20.5  20.8 

500 

400 

14.4 

14.6 

14.8 

15.0 

15.2 

15.4 

15.6 

15.8 

16.0 

16.2 

16.416.6 

400 

300 

10.8 

11.0 

11.1 

11.3 

11.4 

11.6 

11.7 

11.9 

12.0 

12.2 

12.312.5 

300 

200 

7.2 

7.3 

7.4 

7.5 

7.6 

7.7 

7.8 

7.9 

8.0 

8.1 

8.2 

8.3 

200 

100 

3.6 

3.7 

3.7 

3.8 

3.8 

3.9 

3.9 

4.0 

4.0 

4.1 

4.1 

4.2 

100 

90 

3.2 

3.3 

3.3 

3.4 

3.4 

3.5 

3.5 

3.6 

3.6 

3.7 

3.7 

3.7 

90 

80 

2.9 

2.9 

3.0 

3.0 

3.0 

3.11 

3.1 

3.2 

3.2 

3.2 

3.3 

3.3 

80 

70 

2.5 

2.6 

2.6 

2.6 

2.7 

2.7 

2.7 

2.8 

2.8 

2.8 

2.9 

2.9 

70 

60 

2.2 

2.2 

2.2 

2.3 

2.3 

2.3 

2.3 

2.4 

2.4 

2.4 

2.5 

2.5 

60 

50 

1.8 

1.8 

1.9 

1.9 

1.9 

1.9 

2.0 

2.0 

2.0 

2.0 

2.1 

2.1 

50 

40 

1.4 

1.5 

1.5 

1.5 

1.5 

1.5 

1.6 

1.6 

1.6 

1.6 

1.6 

1.7 

40 

30 

1.1 

1.1 

1.1 

1.1 

1.1 

1.2 

1.2 

1.2 

1  2 

1.2 

1.2 

1.2 

30 

20 

.7 

.7 

.7 

.8 

.8 

.8 

.8 

.8 

.8 

.8 

.8 

.8 

20 

10 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

10 

9 

.3 

.3 

.3 

.3 

.3 

.3 

.4 

.4 

.4 

.4 

.4 

.4 

9 

8' 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

8 

7 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

7 

6 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

6 

5 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

5 

4 

.1 

.1 

.1 

o 

.2 

2 

.2 

.2 

.2 

.2 

.2 

.2 

4 

3 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

3 

2 

1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

2 

1 

H 

3.60 

3.65 

3.70 

3.75 

3.80 

3.85 

3.90 

3.95 

4. CO 

4.05 

4.10 

4.15 

i 

Appendix. 


243 


Table  VII.  Pounds  of  fat  in 

1  to  10,000  lbs 

.  of  milk 

{Continued). 

4.20 

4.25 

4.30 

4.35 

4.40 

4.45 

4.50 

4.55 

4.60 

4.65 

4.70 

4.75 

r 

Milk 

Milk 

lbs. 

lbs. 

10,000 

420 

425 

430 

435 

440 

445 

450 

455 

460 

465 

470 

475 

10,000 

9,000 

378 

383 

387 

392 

396 

401 

405 

410 

414 

419 

423 

428 

9,000 

S,000 

336 

340 

344 

348 

352 

856 

860 

864 

368 

372 

376 

380 

8,000 

7,000 

294 

298 

301 

305 

808 

312 

315 

819 

322 

826 

829 

888 

7,000 

6,000 

252 

255 

258 

261 

264 

267 

270 

273 

276 

279 

282 

285 

6,000 

5,000 

210 

213 

215 

218 

220 

228 

225 

228 

230 

283 

235 

238 

5,0(0 

4,000 

168 

170 

172 

174 

176 

178 

180 

182 

184 

186 

188 

190 

4,000 

8,000 

126 

128 

129 

131 

182 

184 

185 

187 

138 

140 

141 

148 

8,000 

2,000 

84.0 

85.0 

86.0 

87.0 

88.0 

89.0 

90.0 

91.0 

92.0 

93.0 

94.0 

95.0 

2,000 

1,000 

42.0 

42.5 

43.0 

43.5 

44.0 

44.5 

45.0 

45.5 

46.0 

46.5 

47.0 

47.5 

1,000 

900 

37.8 

38.3 

38.7 

39.2 

39.6 

40.1 

40.5 

41.0 

41.4 

41.9 

42.3 

42.8 

900 

800 

33.6 

31.0 

34.4 

34.8 

35.2 

35.6 

36.0 

36.4 

36.8 

37.2 

37.  () 

88.0 

800 

700 

29.4 

29.8 

.:50.1 

30.5 

80.8 

31.2 

31.5 

81.9 

32.2 

32.6 

32.9 

88.3 

700 

600 

25.2 

25.5 

5.8 

26.1 

26.4 

26.7 

27.0 

27.8 

27.6 

27.9 

28.2 

28.5 

600 

500 

21.0 

21.3 

21.5 

21.8 

22.0 

22.8 

22.5 

22.8 

23.0 

28.3 

23.5 

23.8 

500 

400 

16.8 

17.0 

17.2 

17.4 

17.6 

17.8 

18.0 

18.2 

18.4 

18.6 

18.8 

19.0 

400 

300 

12.6 

12.8 

12.9 

13.1 

13.2 

13.4 

13.5 

13.7 

13.8 

14.0 

14.1 

14.3 

800 

200 

8.4 

8.5 

8.6 

8.7 

8.8 

8.9 

9.0 

9.1 

9.2 

9.3 

9.4 

9.5 

200 

100 

4.2 

4.3 

4.3 

4.4 

4.4 

4.5 

4.5 

4.6 

4.6 

4.7 

4.7 

4.8 

100 

90 

3.8 

3.8 

3.9 

3.9 

4.0 

4.0 

4.1 

4.1 

4.1 

4.2 

4.2 

4.3 

9-;) 

80 

3.4 

3.4 

3.4 

3.5 

8.5 

3.6 

3.6 

S.iS 

8.7 

3.7 

3.8 

8.8 

80 

70 

2.9 

3.0 

3.0 

3.0 

8.1 

3.1 

3.2 

8.2 

8.2 

3.3 

3.3 

8.8 

70 

60 

2.5 

2.6 

2.6 

2.6 

2.6 

2.7 

2.7 

2.7 

2.8 

2.8 

2.8 

2  9 

60 

50 

2.1 

2.1 

2.2 

2.2 

2  2 

2.2 

2.8 

2.8 

2.3 

2.8 

2.4 

2.4 

50 

40 

1.7 

1.7 

1.7 

1.7 

1^8 

1.8 

1.8 

1.8 

1.8 

1.9 

1.9 

1.9 

40 

30 

1.3 

1.3 

1.3 

1.3 

1.3 

1.8 

1.4 

1.4 

1.4 

1.4 

1.4 

1.4 

30 

20 

.8 

.9 

.9 

.9 

.9 

.9 

.9 

.9 

.9 

.9 

.9 

1.0 

20 

10 

.4 

.4 

.4 

.4 

.4 

.4 

.5 

.5 

.5 

.5 

.5 

.5 

10 

9 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

9 

S 

.3 

.3 

.3 

.3 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

8 

7 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

'.s 

.8 

.3 

7 

6 

.3 

.3 

.3 

.3 

.3 

.3 

.o 

.8 

.3 

.3 

.8 

.8 

6 

5 

.2 

.2 

^2 

.2 

.2 

.2 

.2 

.2 

2 

.2 

2 

2 

5 

4 

.2 

.2 

2 

2 

.2 

.2 

2 

.2 

'.2 

2 

!2 

2 

4 

3 

.1 

.1 

A 

!i 

.1 

.1 

.*1 

.1 

.1 

.1 

.1 

!T 

3 

2 
1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

2 
1 

4.20 

4.25 

4.30 

4.35 

4.40 

4.45 

4.50 

4.55 

4.60 

4.65 

4.70 

4.75 

^ 
^ 

i 

244  Testing  Milk  and  Its  Products. 

Table  VII.    Pounds  of  fat  in  I  to  10,000  lbs.  of  milk  ( Continued), 


*5 

4.80 

4.85 

4.90 

4.95 

5.00 

5.05 

5.10 

5.15 

5.20 

5.25 

5.30 

5.35 

r 

Milk 

Milk 

lbs. 

lbs. 

10,000 

480 

485 

490 

495 

500 

505 

510 

515 

520 

525 

530 

535 

10,000 

9,000 

432 

437 

441 

446 

450 

455 

459 

464 

468 

473 

477 

482 

9,000 

8,000 

384 

388 

392 

396 

400 

404 

408 

412 

416 

420 

424 

428 

8,000 

7,000 

336 

340 

343 

347 

350 

354 

357 

361 

364 

368 

371 

375 

7,000 

6,000 

288 

291 

294 

297 

300 

303 

306 

309 

312 

315 

318 

321 

6,000 

5,000 

240 

243 

245 

248 

250 

253 

255 

258 

260 

263 

265 

268 

5,000 

4,000 

192 

194 

196 

198 

200 

202 

204 

206 

208 

210 

212 

214 

4,000 

8,000 

144 

146 

147 

149 

150 

152 

153 

155 

156 

158 

159 

161 

3,000 

2,000 

96.0 

97.0 

98.0 

99.0 

100 

101 

102 

103 

104 

105 

106 

107 

2,000 

1,000 

48.0 

48.5 

49.0 

49.5 

50.0 

50.5 

51.0 

51.5 

52.0 

52.5 

53.0 

53.5 

1,000 

900 

43.2 

43.7 

44.1 

44.6 

45.0 

45.5 

45.7 

46.4 

46.8 

47.3 

47.7 

48.2 

900 

800 

38.4 

38.8 

39.2 

39.6 

40.0 

40.4 

40.8 

41.2 

41.6 

42.0 

42.4 

42.8 

800 

700 

33.6 

34.0 

34.3 

34.7 

35.0 

35.4 

.35.7 

36.1 

36.4 

36.8 

37.1 

37.5 

700 

600 

28.8 

29.1 

29.4 

29.7 

30.0 

30.3 

30.6 

30.9 

31.2 

31.5 

31.8 

32.1 

600 

500 

24.0 

24.3 

24.5 

24.8 

25.0 

25.3 

25.5 

25.8 

26.0 

26.3 

26.5 

26.8 

500 

400 

19.2 

19.4 

19.6 

19.8 

20.0 

20.2 

20.4 

20.6 

20.8 

21.0 

21.2 

21.4 

400 

300 

14.4 

14.6 

14.7 

14.9 

15.0 

15.2 

15.3 

15.5 

15.6 

15.8 

15.9 

16.1 

300 

200 

9.6 

9.7 

9.8 

9.9 

10.0 

10.1 

10.2 

10.3 

10.4 

10.5 

10.6 

10.7 

200 

100 

4.8 

4.9 

4.9 

5.0 

5.0 

5.1 

5.1 

5.2 

5.2 

5.3 

5.3 

5.4 

100 

90 

4.3 

4.4 

4.4 

4.5 

4.5 

4.5 

4.6 

4.6 

4.7 

4.7 

4.8 

4.8 

90 

80 

3.8 

3.9 

3.9 

4.0 

4.0 

4.0 

4.1 

4.1 

4.2 

4.2 

4.2 

4.3 

80 

70 

3.4 

3.4 

3.4 

3.5 

3.5 

3.5 

3.6 

3.6 

3.6 

3.7 

3.7 

3.7 

70 

60 

2.9 

2.9 

2.9 

3.0 

3.0 

3.0 

3.1 

3.1 

3.1 

3.2 

3.2 

3.2 

60 

50 

2.4 

2.4 

2.5 

2.5 

2.5 

2.5 

2.6 

2.6 

2.6 

2.6 

2.7 

2.7 

50 

40 

1.9 

1.9 

2.0 

2.0 

2.0 

2.0 

2.0 

2.1 

2.1 

2.1 

2.1 

2.1 

40 

30 

1.4 

1.5 

1.5 

1.5 

1.5 

1.5 

1.5 

1.5 

1.6 

1.6 

1.6 

1.6 

30 

20 

1.0 

1.0 

1.0 

1.0 

1.0 

1.0 

1.0 

1.0 

1.0 

1.1 

1.1 

1.1 

20 

10 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

10 

9 

.4 

.4 

.4 

.4 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

9 

S 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

8 

i 

.3 

.3 

.3 

.3 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

7 

0 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

0 

5 

.2 

.2 

.2 

.2 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

5 

4 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

4 

3 

.1 

.1 

.1 

.1 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

3 

o 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

2 

1 

.1 
5.00 

.1 
5.05 

.1 

5.10 

.1 
5.15 

.1 
5.20 

.1 
5.25 

.1 
5.30 

.1 
5.35 

1 

4.80 

4.85 

4.90 

4.95 

1 

1 

Appendix. 


245 


Table  VIII.     Pounds  of  fat  in  I  to  1000  lbs.  of  cream  testing 
12.0  to  50.0  per  cent.  fat. 


(See  directions  for  use,  p.  240.) 


1 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

25 

26 

27 

28 

29 

30 

ii 

1000 

120 

igo 

140 

L50 

160 

170 

180 

190 

200 

210 

220 

230 

240 

2.50 

260 

270 

280 

290 

300 

yoo 

108 

117 

126 

135 

144 

L53 

162 

171 

180 

189 

198 

207 

216 

225 

284 

243 

252 

261 

270 

800 

96 

104 

112 

120 

128 

136 

141 

152 

160 

168 

176 

184 

192 

200 

208 

216 

224 

2:^2 

240 

700 

84 

91 

98 

105 

112 

119 

126 

133 

140 

147 

154 

161 

168 

175 

182 

189 

196 

203 

210 

600 

72 

78 

84 

90 

96 

102 

108 

114 

120 

126 

132 

138 

144 

150 

156 

162 

168 

174 

180 

500 

60 

65 

70 

75 

80 

85 

90 

95 

100 

105 

110 

115 

120 

125 

130 

135 

140 

145 

150 

400 

48 

52 

56 

60 

64 

68 

72 

76 

80 

84 

88 

92 

96 

100 

104 

108 

112 

116 

120 

300 

36 

39 

42 

45 

48 

51 

54 

57 

60 

63 

66 

69 

72 

75 

78 

81 

84 

87 

90 

200 

24 

26 

28 

30 

32 

34 

36 

38 

40 

42 

44 

46 

48 

50 

62 

54 

6b 

58 

60 

100 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

25 

26 

27 

28 

29 

30 

90 

10.8 

11.7 

12.6 

13.5 

14.4 

15.3 

16.2 

17.1 

18.0 

18.9 

19.8 

20.7 

21.6 

22.5 

23.4 

24.3 

25.2 

26.1 

27.0 

80 

9.6 

10.4 

11.2 

12.0 

12.8 

13.6 

14.4 

15.2 

16.0 

16.8 

17.6 

18.4 

19.2 

JO.O 

20.8 

21.6 

22.4 

23.2 

24.0 

70 

8.4 

9.1 

9.8 

10.5 

11.2 

11.9 

12.6 

13.3 

14.0 

14.7 

15.4 

16.1 

16.8 

17.5 

18.2 

18.9 

19.6 

20..3 

21.0 

60 

7.2 

7.8 

8.4 

9.0 

9.6 

10.2 

10.8 

11.4 

12.0 

12.6 

13.2 

13.8 

14.4 

15.0 

15.6 

16.2 

16.8 

17.4 

18.0 

60 

6.0 

6.5 

7.0 

7.5 

8.0 

8.5 

9.0 

9.5 

10.0 

10.5 

11.0 

11.5 

12.0 

12.5 

13.0 

13.5 

14.0 

14.5 

15.0 

40 

4.8 

5.2 

5.6 

6.0 

6.4 

6.8 

7.2 

7.6 

8.0 

8.4 

8.8 

9.2 

9.6 

10.0 

10.4 

10.8 

11.2 

11.6 

12.0 

80 

3.6 

3.9 

4.2 

4.5 

4.8 

5.1 

5.4 

5.7 

6.0 

6.3 

6.6 

6.9 

7.2 

7.5 

7.8 

8.1 

8.4 

8.7 

9.0 

20 

2.4 

2.6 

2.8 

3.0 

3.2 

3.4 

3.6 

3.8 

4.0 

4.2 

4.4 

4.6 

4.8 

5.0 

5.2 

5.4 

5.6 

5.8 

6.0 

10 

1.2 

1.3 

1.4 

1.5 

1.6 

1.7 

1.8 

1.9 

2.0 

2.1 

2.2 

2.3 

2.4 

2.5 

2.6 

2.7 

2.8 

2.9 

3.0 

9 

1.08 

1.17 

1.26 

1.85 

1.44 

1.53 

1.62 

1.71 

1.80 

1.89 

1.98 

2.07 

2.16 

2.25 

2.34 

1.43 

2.52 

2.61 

2.70 

8 

.96 

i.ai 

1.12 

1.20 

1.28 

1.36 

1.44 

1.52 

1.60 

1.68 

1.76 

1.84 

1.92 

2.00 

2.08 

2.16 

2.24 

2.32 

2.40 

7 

.84 

.91 

.9S 

1.05 

1.12 

1.19 

1.26 

1.33 

1.40 

1.47 

1..54 

1.61 

1.68 

1.75 

1.82 

1.89 

1.96 

2.03 

2.10 

6 

.72 

.78 

.84 

.(10 

.96 

1.02 

1.08 

1.14 

1.20 

1.26 

1.32 

1.38 

1.44 

1.50 

1.56 

1.62 

1.68 

1.74 

1.80 

5 

.60 

.65 

.70 

.75 

.85 

.90 

.95 

1.00 

i.a5 

1.10 

1.15 

1.20 

1.25 

1.30 

1 .35 

1.40 

1.45 

1.50 

4 

.48 

.52 

.56 

.60 

!64 

.68 

.72 

.76 

.80 

.84 

.88 

.92 

.96 

1.00 

1.04 

1.08 

1.12 

1.16 

1.20 

8 

.86 

.39 

.42 

.45 

.48 

.51 

.54 

.57 

.60 

.63 

.66 

.69 

.72 

.75 

.78 

.81 

.84 

.87 

.90 

2 

.24 

.26 

.28 

.30 

I32 

.34 

.36 

.38 

.40 

.42 

.44 

.46 

.48 

.50 

.52 

.54 

.56 

.58 

.60 

1 

.12 

.13 

.14 

.15 

.16 

.17 

.18 

.19 

.20 

.21 

.22 

.23 

.24 

.25 

.26 

.27 

.28 

.29 

.80 

246 


Testing  Milk  and  Its  Products. 


Table  VIII.     Pounds  of  fat  in  I  to  1000  lbs.  of  cream  {confimied). 


a  . 

31 

32 

33 

34 

35 

36 

37 

38 

39 

40 

41 

42 

43 

44 

45 

46 

47 

48 

49 

50 

k 

1000 

310 

320 

380 

340 

3.50 

360 

370 

380 

390 

400 

410 

420 

430 

440 

450 

460 

470 

480 

490 

600 

900 

279 

288 

297 

306 

315 

324 

333 

342 

351 

360 

369 

378 

387 

896 

405 

414 

428 

432 

441 

450 

800 

248 

256 

264 

272 

280 

288 

216 

304 

312 

320 

328 

336 

344 

.352 

360 

368 

376 

384 

392 

400 

700 

217 

224 

231 

238 

245 

252 

2;,9 

266 

273 

280 

287 

294 

301 

308 

315 

322 

829 

336 

343 

350 

600 

186 

192 

198 

204 

210 

216 

222 

228 

234 

240 

246 

252 

258 

264 

270 

276 

282 

288 

294 

300 

500 

155 

160 

165 

170 

175 

180 

185 

190 

195 

200 

205 

210 

215 

220 

225 

230 

235 

240 

245 

250 

400 

124 

128 

132 

136 

140 

144 

148 

152 

156 

160 

164 

168 

172 

176 

180 

184 

188 

192 

196 

200 

800 

93 

96 

99 

102 

105 

108 

111 

114 

117 

120 

123 

126 

129 

132 

135 

188 

141 

144 

147 

150 

200 

62 

64 

66 

68 

70 

72 

74 

76 

78 

80 

82 

84 

86 

88 

90 

92 

94 

96 

98 

100 

100 

31 

32 

83 

34 

35 

36 

37 

38 

39 

40 

41 

42 

43 

44 

45 

46 

47 

48 

49 

50 

90 

27.9 

28.8 

29.7 

30.6 

31.5 

32.4 

33.3 

34.2 

35.1 

36.0 

36.9 

37.8 

38.7 

39.6 

40.5 

41.4 

42.3 

48.2 

44.1 

45.0 

80 

24.8 

2i.6 

26.4 

27.2 

28.0 

28.8 

29.6 

30.4 

21.2 

32.0 

32.8 

33.6 

34.4 

35.2 

36.0 

36.8 

37.6 

88.4 

39.2 

40.0 

70 

21.7 

22.4 

23.1 

23.8 

24.5 

25.2 

25.9 

26.6 

27.3 

28.0 

28.7 

29.4 

30.1 

30.8 

31.5 

82.2 

32.9 

33.6 

34.8 

35.0 

60 

18.6 

19.2 

19.8 

20.4 

21.0 

21.6 

22.2 

22.8 

23.4 

24.0 

24.6 

25.2 

25.8 

26.4 

27.0 

27.6 

28.2 

28.8 

29.4 

30.0 

50 

15.5 

16.0 

16.5 

17.0 

17.5 

18.0 

18.5 

19.0 

19.5 

20.0 

20.5 

21.0 

21.5 

22.0 

22.5 

23.0 

23.6 

24.0 

24.5 

25.0 

40 

12.4 

12.8 

13.2 

13.6 

14.0 

14.4 

14.8 

15.2 

15.6 

16.0 

16.4 

16.8 

17.2 

17.6 

18.0 

18.4 

18.8 

19.2 

19.6 

20.0 

30 

9.3 

9.6 

9.9 

10.2 

10.5 

10.8 

11.1 

11.4 

11.7 

12.0 

12.3 

12.6 

12.9 

13.2 

13.6 

13.8 

14.1 

14.4 

14.7 

15.0 

20 

6.2 

6.4 

6.6 

6.8 

7.0 

7.2 

7.4 

7.6 

7.8 

8.0 

8.2 

8.4 

8.6 

8.8 

9.0 

9.2 

9.4 

9.6 

9.8 

10.0 

10 

3.1 

3.2 

3.3 

8.4 

3.5 

8.6 

3.7 

3.8 

3.9 

4.0 

4.1 

4.2 

4.3 

4.4 

4.5 

4.6 

4.7 

4.8 

4.9 

5.0 

9 

2.79 

2.88 

2.97 

3.06 

3.15 

3.24 

3.33 

3.42 

3.51 

3.60 

8.69 

3.78'3.87 

3.96 

4.95 

4.14 

4.23 

4.32 

4.41 

4.50 

8 

2.48 

2.56 

2.64 

2.72 

2.80 

2.88 

2.06 

3.04 

3.12 

3.20 

3.28 

3.363.44 

3.52  3.60 

3.68 

3.76 

3.84 

3.92 

4.00 

7 

2.17 

2.24 

2.81 

2.38 

2.45 

2.52 

2.59 

2.66 

2.73 

2.80 

2.87 

2.943.01 

3.08 

3.15 

3.22 

3.29 

8.36 

3.48 

3.50 

6 

1.86 

1.92 

1.98 

2.04 

2.10 

2.16 

2.22 

2.28 

2.34 

2.40 

2.46 

2.522.58 

2,64 

2.70 

2.76 

2.82 

2.88 

2.94 

3.00 

5 

1.55 

1.60 

1.65 

1.70 

1.75 

1.80 

1.85 

1.90 

1.95 

2.00 

2.05 

2.102.15 

2.20 

2.25 

2.30 

2.35 

2.40 

2.45 

2.50 

4 

1.24 

1.28 

1.32 

1.36 

1.40 

1.44 

1.48 

1.52 

1.56 

1.60 

1.64 

1.68  1.72 

1.76 

1.80 

1.84 

1.88 

1.92 

1.96 

2.00 

3 

.93 

.96 

.99 

1.02 

l.Oo 

1.08 

1.11 

1.14 

1.17 

1.20 

1.23 

1.26  1.29 

1.32 

1.35 

1.88 

1.41 

1.44 

1.47 

1.50 

2 

.62 

.64 

.66 

.68 

.70 

.72 

.74 

.76 

.78 

.80 

.82 

.84  .86 

.88 

.90 

.92 

.94 

.96 

.98 

1.00 

1 

.31 

.32 

j33 

.34 

.35 

.S6 

.37 

.38 

.39 

.40 

.41 

.42  .43 

.44 

.45 

.46 

.47 

.48 

.49 

.50 

Appendix. 


247 


Table    iX.     Amount  due  for  butter  fat,  in  dollars  and  cents,  at 
12  to  25  cents  per  pound. 

(See  directions  for  use,  page  240.) 


Pounds  of  butter  fat. 

1. 

1,000 

900 

800 

700 

600 

500 

400 

300 

200 

100 

-CD 

12 
12i 

121 

13 
13i 
13^ 
13i 

14 
14] 
14i 

14| 

15 
15i 

15.^ 
15i 

16 

16] 
16^ 
16| 

17 
17^ 

17^ 
17f 

18 
18] 
18^ 
181 

1 

120.00 
122.50 
12.5.00 
127.50 

130.00 
132.50 
135.00 
137.50 

140.00 
142.50 
145.00 
147.50 

150.00 
152.50 
155.00 
157.50 

160.00 
162.50 
165.00 
167.50 

170.00 
172.50 
175.00 
177.60 

180.00 
182.50 
185.00 
187.50 

$ 

108.00 
110.25 
112.50 
114.75 

117.00 
119.25 
121.50 
123.75 

126.00 
128.25 
130.50 
132.75 

135.00 
137.25 
139.50 
141.75 

144.00 
146.25 
148.50 
150.75 

153.00 
155.25 
157.50 
159.75 

162.00 
164.25 
166.50 
168.75 

96.00 

98.00 

100.00 

102.00 

104.00 
106.00 
108.00 
110.00 

112.00 
114.00 
116.00 
118.00 

120.00 
122.00 
124.00 
126.00 

128.00 
130.00 
132.00 
134.00 

136.00 
138.00 
140.00 
142.00 

144.00 
146.00 
148.00 
150.00 

1 

84.00 

85.75 
87.50 
89.25 

91.00 

92.75 
94.50 
96.25 

98.00 

99.75 

101.50 

103.25 

105.00 
106.75 
108.50 
110.25 

112.00 
113.75 
115.50 
117.25 

119.00 
120.75 
122.50 
124.25 

126.00 
127.75 
129.50 
131.25 

1 

72.00 
73.50 
75.00 
76.50 

78.00 
79.50 
81.00 
82.50 

84.00 
85.50 
87.00 
88.50 

90.00 
91.50 
93.00 
94.50 

96.00 

97.50 

99.00 

100.50 

102.00 
103.50 
105.00 
106.50 

108.00 
109.50 
111.00 
112.50 

1 

60.00 
61.25 
62.50 
63.75 

65.00 
66.25 
67.50 
68.75 

70.00 
71.25 
72.50 
73.75 

75.00 
76.25 
77.50 

78.75 

80.00 
81.25 

82.50 
83.75 

85.00 
86.25 
87.50 

87.75 

90.00 
91.2.5 
92.50 
93.75 

1 

48.00 
49.00 
50.00 
.51.00 

52.00 
.53.00 
54.00 
55.00 

56.00 
57.00 
58.00 
59.00 

60.00 
61.00 
62.00 
63.00 

64.00 
65.00 
66.00 
67.00 

68.00 
69.00 
70.00 
71.00 

72.00 
73.00 
74.00 
75.00 

$ 

36.00 
36.75 
37.50 
38.25 

39.00 
39.75 
40.50 
41.25 

42.00 
42.75 
43.50 
44.25 

45.00 
45.75 
46.50 
47.25 

48.00 
48.75 
49.50 
50.25 

51.00 
51.75 
.52.50 
53.25 

54.00 
54.75 
55.50 
56.25 

1 

24.00 
24.50 
25.00 
25.50 

26.00 
26.50 
27.00 
27.50 

28.00 
28.50 
29.00 
29.50 

30.00 
30.50 
31.00 
31.50 

32.00 
32.50 
33.00 
33.50 

34.00 
34.50 
35.00 
35.50 

36.00 
36.50 
37.00 
37.50 

12.00 
12.25 
12.50 
12.75 

13.00 
13.25 
13.50 
13.75 

14.00 
14.25 
14.50 
14.75 

15.00 
15.25 
15.50 
15.75 

16.00 
16.25 
16.50 
16.75 

17.00 
17.25 
17.50 
17.75 

18.00 
18.25 
18.50 
18.75 

12 
12i 

11 

13 
13} 

m 

131 

14 

141 
14.^ 
141 

15 
15J 
15^ 
15| 

16 
16J 

III 

17 

in 
17^ 
17| 

18 

18^ 
18^ 
18i 

1,000 

900 

800 

700 

600 

500 

400 

300 

200 

100 

248  Testing  Milk  and  Its  Products. 

lable  IX.       Amount  due  for  butter  fat  {Continued). 


i 

Pounds  of  butter  fct. 

1, 

n 

"a 

1,000 

900 

800 

700 

600 

500 

400 

300 

200 

100 

■   a, 

r 

19 
19] 
19^ 

m 

20 
2O4 
2O2 
20f 

21 

2U 
21^ 
21i 

22 

22i 

22i 

23 
23} 

23^ 
23| 

24 

24} 
24^ 
24f 
25 

$ 

190.00 
192.50 
195.00 
197.50 

200.00 
202.50 
205.00 
207.50 

210.00 
212.50 
215.00 
217.50 

220.00 
222.50 
225.00 
227.50 

230.00 
232.50 
235.00 
237.50 

240.00 
242.50 
245.00 
247.50 
250.00 

171.00 
173.25 

I75.ro 

]77.75 

180.00 
182.25 
184.50 
186.75 

189.00 
191.25 
193.50 
195.75 

198.00 
200.25 
202.50 
204.75 

207.00 
209.25 
211.50 
213.75 

216.00 
218.25 
220.50 
•>>?.75 
225.00 

1.52.00 
154.00 
1.56.00 
158.00 

160.00 
162.00 
KU.OO 
166.00 

168.00 
170.00 
172.00 
174.00 

176.00 

178.00 
180.00 
182.00 

184.00 
186.00 
188.00 
190.00 

192.00 
194.00 
196.00 
198.00 
200.00 

$ 

133.00 
134.75 
136.50 
138.25 

140.00 
141.75 
143.50 
145.25 

147.00 
148.75 
150.50 
152.25 

154.00 
155 . 75 
157.. iiO 
159.25 

161.00 
162.75 
164.50 
166.25 

168.00 
169.75 
171.50 
173.25 
175.00 

114.00 
115.50 
117.00 
118.50 

120.00 
121.50 
123.00 
124.50 

126.00 
127.50 
129.00 
130.50 

132.00 
133.50 
135.00 
130.50 

138.00 
139.50 
141.00 
142.50 

144.00 
145.50 
147.00 
148.50 
150.00 

95.00 
96.25 
97.50 
98.75 

100.00 
101.25 
102.50 
103.75 

105.00 
106.25 
107.50 
108.75 

110.00 
111.25 
112.50 
113.75 

115.00 
116.25 
117.50 
118.75 

120.00 
121.25 
122.50 
123.75 
125.00 

76.00 
77.00 
78.00 
79.00 

80.00 
81.00 
82.00 
83.00 

84.00 
85.00 
86.00 
87.00 

88.00 
89.00 
90.00 
91.00 

92.00 
93.00 
94.00 
95.00 

96.00 
97.00 
98.00 
99.00 
]00.00 

$ 

57.00 
57 ,  75 
58.50 
59.25 

60.00 
60.75 
61.50 
62.25 

63.00 
63.75 
64.50 
65.25 

66.00 
66.75 
67.50 

68.25 

69.00 
69.75 
70.50 
71.25 

72.00 
72.75 
73.;)0 
74.25 
75.00 

$ 

38.00 
38.50 
39.00 
39.50 

40.00 
40.50 
41.00 
41.. 50 

42.00 
42.50 
43.00 
43.50 

44.00 
44.50 
45.00 
45.50 

46.00 
46.50 
47.00 
47.50 

48.00 
48.50 
49.00 
49.50 
50.00 

$ 

19.00 
19.25 
19.50 
19.75 

20.00 
20.25 
20.50 
20.75 

21.00 
21.25 
21.50 
21.75 

22.00 
22.25 

22.50 
22.75 

23.00 
23.25 
23.50 
23.75 

24.00 
24.25 
24.50 
24.75 
25.00 

19 
19i 
19i 
19| 

20 
20} 
20^ 
201 

21 
21} 

21^ 
211 

22 

i 

221 

23 

23} 
23* 
23i 

24 

24} 
24.V 
241 
25 

1,000 

900 

800 

700 

600 

500 

400 

300 

200^ 

100 

Appendix, 


249 


Table   X.     Relative-value  tables. 

(See  directions  for  use,  pp.  196-198. 


h 

Price  of  milli  per  100  pounds,  in  dollars  and  cents. 

3.0 

.30 

.31 

.33 

.34 

.36 

.37 

.39 

.40 

.42 

.43 

.45 

3.1 

.31 

.33 

.34 

.36 

.37 

.39 

.40 

.42 

.43 

.45 

At 

3.2 

.32 

.34 

.35 

.37 

.38 

.40 

.42 

.43 

.45 

.46 

.48 

3.3 

.33 

.35 

.36 

.38 

.40 

.41 

.43 

.45 

.46 

.48 

.49 

3.4 

.34 

.36 

.37 

.39 

.41 

.42 

.44 

.46 

.48 

.49 

.51 

3.5 

.35 

.37 

.88 

.40 

.42 

.44 

.45 

.47 

.49 

.51 

.55 

3.6 

.36 

.38 

.40 

.41 

.43 

.45 

.47 

.49 

.50 

.52 

.54 

3.7 

.37 

.39 

.41 

.43 

.44 

.46 

.4.S 

.50 

.52 

.54 

.55 

3.8 

.38 

.40 

.42 

.44 

.46 

.47 

.49 

.51 

.53 

.55 

.57 

3.9 

.39 

.41 

.43 

.45 

.47 

.49 

.51 

.53 

.55 

.57 

.58 

4.0 

.40 

.42 

.44 

.46 

.48 

.50 

.52 

.54 

.56 

.58 

.6C 

4.1 

.41 

.43 

.45 

.47 

.49 

.51 

.53 

.55 

.57 

.59 

'  .61 

4.2 

.42 

.44 

.46 

.48 

.50 

.52 

.55 

.57 

.59 

.61 

.6.^ 

4.3 

.43 

.45 

.47 

.49 

.52 

.54 

.56 

.58 

.60 

.62 

.64 

4.4 

.44 

.46 

..48 

.51 

.53 

.55 

.57 

.59 

.62 

.64 

.66 

4.5 

.45 

.47 

.49 

.52 

.54 

.56 

.58 

.61 

.63 

.65 

.67 

4.6 

.46 

.48 

.51 

.53 

.55 

.57 

.60 

.62 

.64 

.67 

.6f 

4.7 

.47 

.49 

.52 

.54 

.56 

.59 

.61 

.63 

.66 

.68 

.7C 

4.8 

.48 

.50 

.53 

.55 

58 

.60 

.02 

.65 

.67 

.70 

.72 

4.9 

.49 

.51 

.54 

.56 

.59 

.61 

.04 

.66 

.69 

.71 

.72 

5.0 

.50 

.52 

.55 

.57 

.60 

.62 

.65 

.67 

.70 

.72 

.75 

5.1 

.51 

.54 

.56 

.59 

.61 

.64 

.66 

.69 

.71 

.74 

.76 

5.2 

.52 

.55 

.57 

.60 

.62 

.65 

.08 

.70 

.73 

.75 

.76 

5.3 

.53 

.56 

.58 

.61 

.64 

.66 

.09 

.72 

.74 

,.77 

.79 

5.4 

.54 

.57 

.59 

.62 

.65 

.67 

.70 

.73 

.76 

.78 

.81 

5.5 

.55 

.58 

.60 

.63 

.66 

.69 

.71 

.74 

.77 

.80 

.82 

5.6 

.56 

.59 

.62 

.64 

.67 

.70 

.73 

.76 

.78 

.81 

.84 

5.7 

.57 

.60 

.63 

.66 

.68 

.71 

.74 

.77 

.80 

.83 

.85 

5.8 

.58 

.61 

.64 

.67 

.70 

.72 

.75 

.78 

.81 

.84 

.87 

5.9 

.59 

.62 

.65 

.68 

.71 

.74 

.77 

.80 

.83 

.86 

.88 

6.0 

.60 

.63 

.66 

.00 

.72 

.75 

.78 

.81 

.84 

.87 

.90 

250 


Testing  Milk  and  lU  Products. 


Table    X.    Relative-value  tables  (Co /^^mtted). 


r 

Price  of  milk  per  100  pounds,  in  dollars  and  cents. 

3.0 

.46 

.48 

.49 

.51 

.52 

.54 

.55 

.57 

.58 

.60 

3.1 

.48 

.50 

.51 

.53 

.54 

.56 

.57 

.59 

.60 

.62 

3.2 

.50 

.51 

.53 

.54 

.56 

.58 

.59 

.61 

.62 

.&4 

3.3 

.51 

.53 

.54 

.56 

.58 

.59 

.61 

.63 

.64 

.66 

3.4 

.53 

.54 

.56 

.58 

.59 

.61 

.63 

.65 

.66 

.68 

3.5 

.54 

.56 

.58 

.59 

.61 

.63 

.65 

.66 

.68 

.70 

3.6 

.56 

.58 

.59 

.61 

.63 

.65 

.67 

.68 

.70 

.72 

3.7 

.57 

.59 

.61 

.63 

.65 

.67 

.68 

.70 

.72 

.74 

3.8 

.59 

.61 

.63 

.65 

.66 

.68 

.70 

.72 

.74 

.76 

3.9 

.60 

.62 

.64 

.66 

.68 

.70 

.72 

.74 

.76 

.78 

4.0 

.62 

.64 

.66 

.68 

.70 

.72 

.74 

.76 

.78 

.80 

4.1 

.64 

.66 

.68 

.70 

.72 

.74 

.76 

.78 

.80 

.82 

4.2 

.65 

.67 

.69 

.71 

.73 

.76 

.78 

.80 

.82 

.84 

4.3 

.67 

.69 

.71 

.73 

.75 

.77 

.80 

.82 

.84 

.86 

4.4 

.68 

.70 

.73 

.75 

.77 

.79 

.81 

.84 

.86 

.88 

4.5 

.70 

.72 

.74 

.76 

.79 

.81 

.83 

.85 

.88 

.90 

4.6 

.71 

.74 

.76 

.78 

.80 

.83 

.85 

.87 

.90 

.92 

4.7 

.73 

.75 

.78 

.80 

.82 

.85 

.87 

.89 

.92 

.94 

4.8 

.74 

.77 

.79 

.82 

.84 

.86 

.89 

.91 

,94 

.96 

4.9 

.76 

.78 

.81 

.83 

.86 

.88 

.91 

.93 

^96 

.98 

5.0 

.77 

.80 

.82 

.85 

.87 

.90 

.92 

.95 

.97 

1.00 

5.1 

.79 

.82 

.84 

.87 

.89 

.92 

.94 

.97 

.99 

1.02 

5.2 

.81 

.83 

.86 

.88 

.91 

.94 

.96 

.99 

1.01 

1.04 

5.3 

.83 

.85 

.87 

.90 

.93 

.95 

.98 

1.01 

1.03 

1.06 

5.4 

.84 

.86 

.89 

.92 

.94 

.97 

1.00 

1.03 

1.05 

1.08 

5.5 

.85 

.88 

.91 

.93 

.96 

.99 

1.02 

1.04 

1.07 

1.10 

5.6 

.87 

.90 

.92 

.95 

.98 

1.01 

1.04 

1.06 

1.09 

1.12 

5.7 

.88 

.91 

.94 

.97 

1.00 

1.03 

1.05 

1.08 

1.11 

1.14 

5.8 

.90 

.93 

.96 

.99 

1.01 

1.04 

1.07 

1.10 

1.13 

1.16 

5.9 

.91 

.94 

.97 

1.00 

1.03 

1.06 

1.09 

1.12 

1.15 

1.18 

6.0 

.93 

.96 

.99 

1.02 

1.05 

1.08 

1.11 

1.14 

1.17 

1.20 

Appendix. 


251 


Table   X.    Relative-value  tables  {Continued). 


Price  of  milk  per  106  pounds,  in  dollars  and  cents. 

3.0 

.61 

.63 

.64 

.66 

.67 

.69 

.70 

.72 

.73 

.75 

3.1 

.64 

.65 

.67 

.68 

.70 

.71 

.73 

.74 

.76 

.78 

3.2 

.66 

.67 

.69 

.70 

.72 

.74 

.75 

.77 

.78 

.80 

3.3 

.68 

.69 

.71 

.73 

.74 

.76 

.78 

.79 

.81 

.83 

3.4 

.70 

.71 

.73 

.75 

.76 

.78 

.80 

.82 

.83 

.85 

3.5 

.72 

.73 

.75 

.77 

.79 

.80 

.82 

.84 

.86 

.88 

3.6 

.74 

.76 

.77 

.79 

.81 

.83 

.85 

.86 

.88 

.90 

3.7 

.76 

.78 

.80 

.81 

.83 

.85 

.87 

.89 

.91 

.93 

3.8 

.78 

.80 

.82 

.84 

.85 

.87 

.89 

.91 

.93 

.95 

3.9 

.80 

.82 

.84 

.86 

.88 

.90 

.92 

.94 

.96 

.98 

4.0 

.82 

.84 

.86 

.88 

.90 

.92 

.94 

.96 

.98 

1.00 

4.1 

.84 

.86 

.88 

.90 

.92 

.94 

.90 

.98 

1.00 

1.03 

4.2 

.86 

.88 

.90 

.92 

.94 

.97 

.99 

1.01 

1.03 

1.05 

4.3 

.88 

.90 

.92 

.95 

.97 

.99 

1.01 

l.t)3 

1.05 

1.08 

4.4 

.90 

.92 

.95 

.97 

.99 

1.01 

1.03 

1.06 

1.08 

1.10 

4.5 

.92 

.94 

.97 

.99 

1.01 

1.03 

1.06 

1.08 

1.10      1.13 

4.6 

.94 

.97 

.99 

1.01 

1.03 

1.06 

1.08 

1.10 

1.13 

1.15 

4.7 

.96 

.99 

1.01 

1.03 

1.06 

1.08 

1.10 

1.13 

1.15 

1.18 

4.8 

.98 

1.01 

1.03 

1.06 

1.08 

1.10 

1.13 

1.15 

1.18 

1.20 

4.9 

1.00 

1.03 

1.05 

1.08 

1.10 

1.13 

1.15 

1.18 

1.20 

1.23 

5.0 

1.02 

1.05 

1.07 

1.10 

1.12 

1.15 

1.18 

1.20 

1.23 

1.25 

5.1 

1.05 

1.07 

1.10 

1.12 

1.15 

1.17 

1.20 

1.22 

1.25 

1.27 

5.2 

1.07 

1.09 

1.12 

1.14 

1.17 

1.20 

1.22 

1.25 

1.27 

1.30 

5.3 

1.09 

1.11 

1.14 

1.17 

1.19 

1.22 

1.25 

1.27 

1.30 

1.32 

5.4 

1.11 

1.13 

1.16 

1.19 

1.21 

1.24 

1.27 

1.30 

1.32 

1.35 

5.5 

1.13 

1.15 

1.18 

1.21 

1.24 

1.26 

1.29 

1.32 

1.35 

1.38 

5.6 

1.15 

1.18 

1.20 

1.23 

1.26 

1.29 

1.32 

1.34 

1.37 

1.40 

5.7 

1.17 

1.20 

1.23 

1.25 

1.28 

1.31 

1.34 

1.37 

1.39 

1.43 

5.8 

1.19 

1.22 

1.25 

1.28 

1.30 

1.33 

1.3(j 

1.39 

1.42 

1.45 

5.9 

1.21 

1.24 

].27 

1.30 

1.33 

1.36 

1.39 

1.42 

1.45 

1.48 

6.0 

1.23 

1.26 

1.29 

1.32 

1.35 

1.38 

1.41 

1.44 

1.47 

1.50 

252 


Testing  Milk  and  Its  Products. 


Table   X.    Relative-value  tables  {^Continued). 


Price  of  milk  per  100  pounds,  in  dollars  and  cents. 


.70 
.79 
.82 
.84 

.87 

.89 
.92 
.94 
.r7 
.99 

1.02 
1.05 
1.07 
1.10 
1.12 

1.15 
1.17 
1.20 
1.22 
1.25 

1.27 
1.30 
1.33 
1.35 
1.38 

1.40 
1.43 
1.45 
1.48 
1.50 
1.53 


.81 

.88 
.86 

.88 

.91 
.94 
.96 
.99 
1.01 

1.04 
1.07 
1.09 
1.12 
1.14 

1.17 
1.20 
1.22 
1.2.5 
1.27 

1;30 

1.33 
1.35 

1.38 
1.40 

1.43 
1.46 
1.48 
1.51 
1.53 
1.50 


.79 

.81 

.82 

.84 

.85 

.87 

.88 

.82 

.84 

.85 

.87 

.88 

.90 

.91 

.85 

.80 

.88 

.90 

.91 

.93 

.94 

.87 

.89 

.91 

.92 

.94 

.96 

.97 

.90 

.92 

.93 

.95 

.97 

.99 

1.00 

.93 

.94 

.96 

.98 

1.00 

1.01 

1.03 

.95 

.97 

.99 

1.00 

1.03 

1.04 

1.06 

.98 

1.00 

1.02 

1.03 

1.05 

1.07 

1.09 

1.01 

1.03 

1.04 

1.06 

1.08 

1.10 

1.12 

1.03 

1.05 

1.07 

1.09 

1.11 

1.13 

1.15 

1.03 

1.08 

1.10 

1.12 

1.14 

1.16 

1.18 

1.09 

1.11 

1.13 

1.15 

1.17 

1.19 

1.21 

1.11 

1.13 

1.15 

1.18 

1.20 

1.22 

1.24 

1.14 

1.10 

1.18 

1.20 

1.23 

1.25 

1.27 

1.17 

1.19 

1.21 

1.23 

1.25 

1.28 

1.30 

1.19 

1.21 

1.24 

1.26 

1.26 

1.30 

1.33 

1  22 

1.24 

1.26 

1.29 

1.31 

1.33 

1.36 

i;25 

1.27 

1.29 

1.32 

1.34 

1.36 

1.39 

1.27 

1.30 

1.32 

1.34 

1.37 

1.39 

1.42 

1.30 

1.32 

1.35 

1.37 

1.40 

1.42 

1.45 

1.32 

1.35 

1.37 

1.40 

1.42 

1.4.5 

1.47 

1.35 

1.38 

1.40 

1.43 

1.45 

1.48 

1.50 

1.37 

1.40 

1.43 

1.46 

1.48 

1.51 

1.53 

1.40 

1.43 

1.46 

1.48 

1.51 

1.54 

1.56 

1.43 

1.46 

1.48 

1.51 

1.54 

1.57 

1.59 

1.40 

1.48 

1.51 

1.54 

1.57 

1.60 

1.62 

1.48 

1.51 

1.54 

1.57 

1.60 

1.62 

1.65 

1.51 

1.54 

1.57 

1.60 

J.  62 

1.65 

1.68 

1.54 

1.57 

1.59 

1.62 

1.65 

1.68 

1.71 

1.50 

1.59 

1.62 

1.65 

1.68 

1.71 

1.74 

1.59 

1.62 

1.G5 

1.68 

1.71 

1.74 

1.77  I 

.90 
.93 
.96 
.99 
1.02 

1.05 
1.08 
1.11 
1.14 
1.17 

1.20 
1.23 
1.26 
1.29 
1.32 

1.35 
1.38 
1.41 
1.44 
1.47 

1.50 
1.53 
1.56 
1.59 
1.62 

1.65 
1.68 
1.71 
1.74 
1.77 
1.80 


Appendix.  253 

Table  XI.  Butter  chart,  showing  calculated  yield  of  butter  (in 
lbs.)  from  I  to  10,000  lbs.  of  milk,  testing  3.0  to  5.3  per 
cent.     (See  directions  for  use,  p.  240.) 


4i 

1 

3.00 

3.10 

3.20 

3.30 

3.40 

3.50 

3.60 

3.70 

3.80 

3.90 

4.00 

4.10 

Milk, 

Milk, 

lbs. 

lbs. 

10,000 

325 

336 

348 

360 

371 

383 

394 

406 

418 

429 

441 

452 

10,000 

9,000 

293 

302 

313 

324 

334 

345 

355 

365 

376 

386 

397 

407 

9,000 

8,000 

260 

269 

278 

288 

297 

306 

315 

325 

334 

343 

353 

362 

8,000 

7,000 

228 

235 

244 

252 

260 

268 

276 

284 

293 

300 

309 

316 

7,000 

6,000 

195 

202 

209 

216 

223 

230 

236 

244 

251 

257 

265 

271 

6,000 

5,000 

163 

168 

174 

180 

186 

192 

197 

203 

209 

215 

221 

226 

5,000 

4,000 

130 

134 

139 

144 

148 

153 

158 

162 

167 

172 

176 

181 

4,000 

3,000 

97.5 

101 

104 

108 

111 

115 

118 

122 

125 

129 

132 

136 

3,000 

2,000 

65.0 

67.2 

69.6 

72.0 

74.2 

76.6 

78.8 

81.2 

83.6 

85.8 

88.2 

90.4 

2,000 

1,000 

32.5 

33.6 

34.8 

36.0 

37.1 

38.3 

39.4 

40.6 

41.8 

43.9 

44.1 

45.2 

1,000 

900 

29.3 

30.2 

31.3 

32.4 

33.4 

34.5 

35.5 

36.5 

37.6 

38.6 

39.7 

40.7 

900 

800 

26.0 

26.9 

27.8 

28.8 

29.7 

30.6 

31.5 

32.5 

33.4 

34.3 

35.3 

36.2 

800 

700 

22.8 

23.5 

24.4 

25.2 

26.0 

26.8 

27.6 

28.4 

29.3 

30.0 

30.9 

31.6 

700 

600 

19.5 

20.2 

20.9 

21.6 

22.3 

23.0 

23.6 

24.4 

25.] 

25.7 

26.5 

27.1 

600 

500 

16.3 

16.8 

17.4 

18.0 

18.6 

19.2 

19.7 

20.3 

20.9 

21.5 

22.1 

22.6 

500 

400 

13.0 

13.4 

13.9 

14.4 

14.8 

15.3 

15.8 

16.2 

16.7 

17.2 

17.6 

18.1 

400 

300 

9.7 

10.1 

10.4 

10.8 

11.1 

11.5 

11.8 

12.2 

12.5 

12.9 

13.2 

13.6 

300 

200 

6.5 

6.7 

6.9 

7.2 

7.4 

7.6 

7.9 

8.1 

8.3 

8.6 

8.8 

9.0 

200 

100 

3.2 

3.4 

3.5 

3.6 

3.7 

3.8 

3.9 

4.1 

4.2 

4.3 

4.4 

4.5 

100 

90 

2.9 

3.0 

3.1 

3.2 

3.3 

3.4 

3.5 

3.6 

3.7 

3.8 

3.9 

4.1 

90 

80 

2.6 

2.7 

2.8 

2.9 

3.0 

3.1 

3.2 

3.3 

3.4 

3.4 

3.5 

3.6 

80 

70 

2.3 

2.3 

2.4 

2.5 

2.6 

2.7 

2.8 

2.8 

2.9 

3.0 

3.1 

3.2 

70 

60 

1.9 

2.0 

2.1 

2.2 

2.2 

2.3 

2.4 

2.4 

2.5 

2.6 

2.7 

2.7 

60 

50 

1.6 

1.7 

1.7 

1.8 

1.9 

1.9 

2.0 

2.0 

2.1 

2.2 

2.2 

2.3 

50 

40 

1.3 

1.3 

1.4 

1.4 

1.5 

1.5 

1.6 

1.6 

1.7 

1.7 

1.8 

1.8 

40 

30 

1.0 

1.0 

1.0 

1.1 

1.1 

1.2 

1.2 

1.2 

1.3 

1.3 

1.3 

1.4 

30 

20 

.6 

.7 

.7 

.7 

.7 

.8 

.8 

.8 

.8 

.9 

.9 

.9 

20 

10 

.8 

.3 

.4 

A 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

.5 

10 

9 

.3 

.3 

.3 

.3 

.3 

.3 

.4 

.4 

.4 

.4 

.4 

.4 

9 

8 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.4 

.4 

8 

7 

.2 

.2 

.2 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

7 

6 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.3 

.3 

.3 

.3 

6 

5 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

5 

4 

.1 

.1 

.1 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

4 

3 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

3 

2 
1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

2 
1 

i 

3.00 

3.10 

3.20 

3.30 

3.40 

3.50 

3.60 

3.70 

3.80 

3.00 

4.00 

4.10 

t 

254 


Testing  Milk  and  Its  Products, 


Ta 

bleX 

.  Butter  chart 

( Continued), 

i 

4.20 

4.30 

4.40 

4.50 

,4.60 

4.70 

4.80 

4.90 

5.00 

5.10 

5.20 

5.30 

r 

Milk 

Milk 

lbs. 

lbs. 

10,000 

464 

476 

487 

499 

510 

522 

534 

545 

557 

568 

580 

592 

10,000 

9,000 

418 

428 

438 

449 

459 

470 

481 

491 

501 

511 

522 

533 

9,000 

8,000 

371 

381 

390 

3i)9 

408 

418 

427 

436 

446 

454 

464 

474 

8,000 

7,000 

325 

333 

341 

349 

357 

365 

374 

382 

390 

398 

406 

414 

7,000 

6,000 

278 

286 

292 

2:)9 

306 

313 

320 

327 

334 

341 

348 

355 

6,000 

5,000 

232 

238 

244 

250 

255 

261 

267 

273 

279 

284 

290 

296 

5,000 

4,000 

186 

190 

195 

200 

204 

209 

214 

218 

223 

227 

232 

237 

4,000 

3,000' 

139 

143 

146 

150 

153 

157 

160 

164 

167 

170 

174 

178 

3,000 

2,000| 

92.8 

95.2 

97.4 

99.8 

102 

104 

107 

109 

111 

114 

116 

118 

2,000 

1,000 

46.4 

47.6 

48.7 

49.9 

51.0 

52.2 

53.4 

54.5 

55.7 

56.8 

58.0 

59.2 

1,000 

900 

41.8 

42.8 

43.8 

44.9 

45.9 

47.0 

48.1 

49.1 

50.1 

.51.1 

52.2 

.53.3 

900 

800 

37.1 

38.1 

39.0  39.9 

40.8 

41.8 

42.7 

43.6 

44.6 

45.4 

46.4 

47.4 

800 

700 

32.5 

33.3 

34.134.9 

35.7 

36.5 

37.4 

38.2 

39.0 

39.8 

40.6 

41.4 

700 

600 

27.8 

28.6 

29.2  29 '.9 

30.6 

31.3 

32.0 

32.7 

33.4 

34.1 

34.8 

35.5 

600 

500 

23.2 

23.8 

24.4  25.0 

25.5 

26.1 

26.7 

27.3 
21.8 

27.9 

28.4 

29.0 

29.6 

500 

400 

18.6 

19.0 

19.5 

20.0 

20.4 

20.9 

21.4 

22.3 

22.7 

23.2 

23.7 

400 

300 

13.9 

14.3 

14.6 

15.0 

15.3 

15.7 

16.0 

16.4 

16.7 

17.0 

17.4 

17.8 

300 

200 

9.3 

9.5 

9.7 

10.0 

10.2 

10.4 

10.7 

10.9 

11.1 

11.4 

11.6 

11.8 

200 

100 

4.6 

4.8 

4.9 

5.0 

5.1 

5.2 

5.3 

5.5 

5.6 

5.7 

5.8 

5.9 

100 

90 

4.2 

4.3 

4.4 

4.5 

4.6 

4.7 

4.8 

4.9 

5.0 

5.1 

5.2 

5.3 

90 

80 

3.7 

3.8 

3.9 

4.0 

4.1 

4.2 

4.3 

4.4 

4.5 

4.5 

4.6 

4.7 

80 

70 

3.3 

3.3 

3.4 

3.5 

3.6 

3.7i 

3.7 

3.8 

3.9 

4.0 

4.1 

4.1 

70 

60 

2.S 

2.9 

2.9 

3.0 

3.1 

3.l| 

3.2 

3.3 

3.3 

3.4 

3.5 

3.6 

60 

50 

2.3 

2.4 

2.4 

2.5 

2.6 

2.6 

2.7 

2.7 

2.8 

2.8 

2.9 

3.0 

50 

40 

1.9 

1.9 

2.0 

2.0 

2.0 

2.1 

2.1 

2  2 

2.2 

2.3 

2.3 

2.4 

40 

30 

1.4 

1.4 

1.5 

1.5 

1.5 

1.6 

1.6 

i^e 

1.7 

1.7 

1.7 

1.8 

30 

20 

.9 

1.0 

1.0 

1.0 

1.0 

1.0 

1.1 

1.1 

1  1 

1.1 

1.2 

1.2 

20 

10 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

.6 

.6 

.6 

.6 

.6 

10 

9 

.4 

.4 

.4 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

9 

8 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

.5 

.5 

.5 

.5 

8 

7 

.3 

.3 

.3 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

7 

6 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.4 

.4 

6 

5' 

.2 

.2 

.2 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

5 

4 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

4 

3 

.1 

.1 

.2 

.2 

2 

.2 

.2 

.2 

.2 

2 

.2 

2 

3 

2 

.1 

.1 

.1 

.1 

\\ 

.1 

.1 

.1 

.1 

A 

.1 

!i 

2 

1 

.1 

4.20 

.1 

4.30 

.1 
4.40 

.1 
4.50 

.1 
4.60 

.1 

4.70 

.1 

4.80 

.1 
4.90 

.1 

5. CO 

.1 
5.10 

.1 
5.20 

.1 

5.30 

1 

1 

t 

Appendix. 


255 


Table  Xll.  Overrun  table,  showing  pounds  of  butter  from 
one  hundred  lbs.  of  milk.  (See  directions  for  use, 
p.  ISr.) 


Per 

cent. 

1.10 

1.11 

1.12 

1.13 

1.14 

1.15 

1.1(5 

1.17 

1.18 

1.19 

1.20 

Per 

cent. 

fat. 

3.30 

3.33 

3.36 

3.39 

3.42 

3.45 

3.48 

3.51 

3.54 

3.57 

3.60 

fat. 

3.0 

3.0 

3.1 

3.41 

3.44 

3.47 

3.50 

3.53 

3.57 

3.60 

3.63 

3.66 

3.68 

3.72 

3.1 

3.2 

3.52 

3.55 

3.58 

3.62 

3.65 

3.68 

3.71 

3.74 

3.78 

3.81 

3.84 

3.2 

3.3 

3.63 

3.66 

3.70 

3.73 

3.76 

3.80 

3.83 

3.86 

3.89 

3.93 

3.96 

3.3 

3.4 

3.74 

3.77 

3.81 

3.84 

3.88 

3.91 

3.94 

3.98 

4.01 

4.05 

4.08 

3.4 

3.5 

3.85 

3.89 

3.92 

3.96 

3.99 

4.03 

4.06 

4.10 

4.13 

4.17 

4.20 

3.5 

3.6 

3.9G 

4.00 

4.03 

4.07 

4.10 

4.14 

4.18 

4.21 

4.25 

4.28 

4.32 

3.6 

3.7 

4.07 

4.11 

4.14 

4.18 

4.22 

4.26 

4.29 

4.33 

4.37 

4.40 

4.44 

3.7 

3.8 

4.18 

4.22 

4.26 

4.29 

4.33 

4.37 

4.41 

4.45 

4.48 

4.52 

4.56 

3.8 

3.9 

4.29 

4.33 

4.37 

4.41 

4.45 

4.49 

4.52 

4.50 

4.60 

4.64 

4.68 

3.9 

4.0 

4.40 

4.44 

4.48 

4.52 

4.56 

4.60 

4.64 

4.68 

4.72 

4.76 

4.80i 

4.0 

4.1 

4.51 

4.55 

4.59 

4.03 

4.67 

4.72 

4.76 

4.80 

4.84 

4.88 

4.92 

4.1 

4.2 

4.62 

4.66 

4.70 

4.75 

4.79 

4.83 

4.87 

4.91 

4.96 

5.00 

5.04 

4.2 

4.3 

4.73 

4.77 

4.82 

4.86 

4.90 

4.95 

4.99 

5.03 

5.07 

5.12 

5.16 

4.3 

4.4 

4.84 

4.88 

4.93 

4.97 

5.02 

5.06 

o.lO 

5.15 

5.19 

5.24 

5.28 

4.4 

4.5 

4.95 

5.00 

5.04 

5.09 

5.13 

5.18 

5.22 

5.27 

5.31 

5.36 

5.40 

4.5 

4.6 

5.06 

5.11 

').15 

5.20 

5.24 

5.29 

5.34 

5.38 

5.43 

5.47 

5.52 

4.6 

4.7 

5.17 

5.22 

5.26 

5.31 

5.36 

5.41 

5.45 

5.49 

5.55 

5.59 

5.64 

4.7 

4.8 

5.28 

5.33 

5.38 

5.42 

5.47 

5.52 

5.57 

5.62 

5.66 

5.71 

5.7H 

4.8 

4.9 

5.39 

5.44 

5.49 

5.54 

5.59 

5.64 

5.68 

5.73 

5.78 

5.83 

5.88 

4.9 

5.0 

5.50 

5.55 

5.60 

5.65 

5.70 

5.75 

5.80 

5.85 

5.90 

5.95 

6.00 

5.0 

5.1 

5.61 

5.66 

5.71 

5.76 

5.81 

5.87 

5.92 

5.97 

6.02 

6.07 

6.12 

5.1 

5.2 

5.72 

5.77 

5.82 

5.88 

5.93 

5.98 

6.03 

6.08 

6.14 

6.19 

6.24 

5.2 

5.3 

5.83 

5.88 

5.94 

5.99 

6.04 

6.10 

6.15 

6.20 

6.2-5 

6.31 

6.36 

5.3 

5.4 

5.94 

5.99 

6.05 

6.10 

6.16 

6.21 

6.26 

6.32 

6.37 

6.43 

6.48 

5.4 

5.5 

6.05 

6.11 

6.16 

6.22 

6.27 

6.33 

6.38 

6.44 

6.49 

6.55 

6.60 

5.5 

5.6 

6.16 

6.22 

6.27 

6.33 

6.38 

6.44 

6.50 

6.55 

6.61 

6.66 

6.72 

5.6 

5.7 

6.27 

6.33 

6.38 

6.44 

6.50 

6.56 

6.61 

6.67 

6.73 

6.78 

6.84 

5.7 

5.8 

6.38 

6.44 

6.50 

8.55 

6.61 

6.67 

6.73 

6.79 

6.84 

6.90 

6.96 

5.8 

5.9 

6.49 

6.55 

6.61 

6.67 

6.73 

6.79 

6.84 

6.90 

6.96 

7.02 

7.08 

5.9 

6.0 

6.60 

6.66 

6.72 

6.78 

r^M 

6.90 

6.96 

7.02 

7.08 

7.14 

7.20 

6.0 

256 


Testing  Milk  and  Its  Products. 


Table  XIII.  Yield  of  cheese,  correspond'ng  to  2.5  to  6  percent, 
of  fat,  with  lactometer  readings  from  26  to  36.   (See  p.  188.) 


*3       . 

Lactometer  degrees. 

+i 

1= 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 

36 

13 

2J> 

7.28 

7.41 

7.54 

7.67 

7.8' 

7.94 

8.07 

8.20 

8.33 

8.47 

8.60 

2.5 

2.(i 

7.44 

7.^7 

7.7t» 

7.83 

7.96 

8.<9 

8.22 

8.35 

8.49 

8.62 

8.76 

2.6 

2.7 

7.5i' 

7.72 

7.85 

7.99 

8.1V 

8.25 

8.38 

8.51 

8.64 

8.77 

8.91 

2.7 

2.b 

7.74 

7.87 

8.00 

8.14 

8.27 

8.40 

8.53 

8.67 

8.80 

8.91 

9.07 

2.8 

2.<) 

7.9t. 

8.03 

8.16 

8.30 

8.44 

8.56 

8.69 

8.82 

8.95 

9.09 

9.22 

2.9 

3.0 

S.Oo 

8.18 

8.31 

8.4--> 

8.58 

8.71 

8. '84 

8.97 

9.11 

9.24 

9.37 

3.0 

3.1 

8.21 

8.34 

8.47 

8.60 

8.74 

8.87 

9.00 

9.13 

9.26 

9.39 

9.53 

3.1 

■^r2 

8.36 

8.1H 

^ .  62 

8.75 

8.89 

9.02 

9.15 

9.28 

9.42 

9.55 

9.68 

3.2 

3.^ 

8.52 

8.65 

8.78 

8.91 

9.05 

9.18 

9.31 

9.44 

9.57 

9.70 

9.84 

3.3 

3.4 

8.07 

8.80 

8.93 

9.06 

9.20 

9.33 

9.46 

9.59 

9.73 

9.86 

9.99 

3.4 

3.^ 

8.82 

8.96 

9.09 

9.22 

9.35 

9.  '8 

9.62 

9.75 

9.88 

10.01 

10,15 

3.5 

3.G 

8.98 

9.11 

9.21 

9.3. 

9.50 

9.63 

9.7: 

9.1)0 

10.03 

10.17 

10.30 

3.6 

3.7 

9.13 

9.26 

9.39 

9.52 

9.65 

9.78 

9.92 

10.05 

10.19 

10.32 

10.46 

3.7 

3.' 

9.29 

9.42 

9.55 

9.68 

,9.81 

9.94 

10. O.N 

1(^21 

10.34 

10.48 

10.61 

3.8 

3.1) 

9.44 

9.57 

9.70 

9.84 

9.97 

10.10 

10.23 

10.36 

10.50 

10.64 

10.77 

3.9 

4.0 

9.60 

9.73 

9.86 

10.00 

10.13 

10.26 

10.39 

10.53 

10.66 

10.79 

10.93 

4.0 

4.1 

9.75 

9.88 

10.02 

.0.15 

10. 2S 

10.39 

10.54 

10.68 

10.81 

10.94 

11.08 

4.1 

4.2 

9.90 

H>.03 

10.17 

10.30 

10.43 

10.57 

10.70 

10.84 

10.97 

11.10 

11.24 

4.2 

4.3 

10.06 

10.19 

10.32 

10.45 

U).58 

10.72 

10.85 

10.99 

11.12 

11.25 

11.39 

4.3 

4.4 

10.21 

10.34 

10.48 

10.61 

10.74 

10.87 

11.00 

11.14 

11.27 

11.41 

11.55 

4.4 

4.5 

io.:^6 

10.49  10.63 

10.76 

10.89 

11.03 

11.16 

11.29 

11.42 

11.56 

11.70 

4.5 

4.(5 

10.52 

10.65 

10. 7^ 

10.92 

11.05 

11.18 

11.31 

11.45 

11.58 

11.71 

11.85 

4.6 

4.7 

10.67 

10.81 

10.94 

11.07 

11.20 

11.34 

11.47 

11.60 

11.73 

11.87 

12.01 

4.7 

4.8 

10. S3 

10.96 

11.09 

11.22 

11.36 

11.49 

11.62 

11.76 

11.89 

12.02 

12.16 

4.8 

4.9 

10. 9H 

11.11 

11.25 

11.3s 

11.51 

11.65 

11.78 

11.91 

12.04 

12.18 

12.32 

4.9 

5.( 

11.14 

11.27 

11.40 

11.54 

11.67 

11.80 

11.93 

12.07 

12.20 

12.34 

12.48 

5.0 

5.1 

11 -.29 

11.42 

11.55 

11.69 

11.82 

11.96 

12.09 

12.23 

12.36 

12.49 

12.63 

5.1 

5. 'J 

11. 4o 

11.58 

11.71 

n.8> 

11.98 

12.11 

12.24 

12.38 

12.52 

12.66 

12.80 

5.2 

5.3 

11.60 

11.73 

11.8(1 

11.99 

12.13 

12.27 

12. '40 

12.53 

12.67 

12.71 

12.85 

5.3 

^.4 

11.76 

11.8912.02 

12.16 

r2.2i» 

12.42 

12.55 

12.69 

12.83 

12.97 

(3.01 

5.4 

5.5 

11.91 

12.04 

12.17 

12.31 

12.44 

12.58 

12.71 

12.85 

12.99 

13.12 

13.25 

5.5 

>.  J 

12.07 

12.20 

12.33 

12.47 

12.60 

12.73 

12.87 

13.00 

13.14 

13.28 

13.41 

5.6 

5.: 

12.22 

12.35 

12.48 

12.62 

12.75 

12.89 

13.02 

13.16 

13.30 

13.44 

13.57 

■>.7 

5.8 

12. 38112.51 

12.64 

12.77 

12.91 

13.05 

13.18 

13.31 

13.45 

13.69 

13.72 

5.8 

5.1* 

I2.53r2.66'l2.79 

12.93 

13.06 

13.19 

13.33 

13.47 

13.60 

13.74 

13.87 

5,9 

0.( 

12. 6y  12.82  12.95 

13.09 

13.22 

13.35 

13.49 

13.62 

13.75 

13.89 

14.02 

6.0 

Appendix. 


257 


Table   XIV.    Comparisons  of  Fahrenheit  and  Centigrade 
(Celsius)  thermometer  scales. 


Fahren- 

Centi- 

Fahren- 

Centi- 

Fahren- 

Centi- 

heit. 

grade. 

heit. 

grade. 

heit. 

grade. 

+212 

+100 

+176 

+80 

+140 

+60 

211 

99.44 

175 

79.44 

139 

59.44 

210 

98.89 

174 

78.89 

138 

58.89 

209 

98.33 

173 

78.33 

137 

58.33 

208 

97.78 

172 

77.78 

136 

57.78 

207 

97.22 

171 

77.22 

135 

57.22 

206 

96.67 

170 

76.67 

134 

56.67 

205 

96.11 

169 

76.11 

133 

56.11 

204 

95.55 

168 

75.55 

132 

55.55 

203 

95 

167 

75 

131 

55 

202 

94.44 

166 

74.44 

130 

54.44 

201 

93.89 

165 

73.89 

129 

53.89 

200 

93.33 

164 

72.33 

128 

53.33 

199 

92.78 

163 

72.78 

127 

52.78 

198 

92.22 

162 

71.22 

126 

62.22 

197 

91.67 

161 

71.67 

125 

51.67 

196 

91.11 

160 

71.11 

124 

51.11 

195 

90.55 

159 

70.55 

123 

50.55 

194 

90 

158 

70 

122 

50 

193 

89.44 

157 

69.44 

121 

49.44 

192 

88.89 

156 

68.89 

120 

48.89 

191 

88.33 

155 

68.33 

119 

48.33 

190 

87.78 

154 

67.78 

118 

47.78 

189 

87.22 

153 

67.22 

117 

47.22 

188 

86.67 

152 

66.67 

116 

46.67 

187 

86.11 

151 

66.11 

115 

46.11 

186 

85.55 

150 

65.55 

114 

45.55 

185 

85 

149 

65 

113 

45 

184 

84.44 

148 

64.44 

112 

44.44 

183 

83.89 

147 

63.89 

111 

43.89 

182 

83.33 

146 

63.33 

110 

43.33 

181 

82.78 

145 

62.78 

109 

42.78 

180 

82.22 

144 

62.22 

108 

42.22 

179 

81.67 

143 

61.67 

107 

41.67 

178 

81.11 

142 

61.11 

-    106 

41.11 

177 

80.55 

141 

60.55 

105 

40.55 

258 


Testing  Milk  and  Its  Products. 


Table  XIV.    Comparisons  of  thermometer  scales  {Continued.) 


Fahren- 

Centi- 

Fahren- 

Centi- 

Fahren- 

Centi- 

heit. 

grade. 

heit. 

grade. 

heit. 

grade. 

+104 

+40 

+68 

+20 

+32 

+0 

103 

39.44 

67 

19.44 

31 

—0.55 

102 

38.89 

66 

18.89 

30 

i.n 

101 

38.33 

65 

18.33 

29 

1.67 

100 

37.78 

64 

17.78 

28 

2.22 

09 

37.22 

63 

17.22 

27 

2.78 

DS 

36.67 

62 

16.67 

26 

3.33 

97 

36.11 

61 

16.11 

25 

3.89 

96 

35.55 

60 

15.55 

24 

4.44 

95 

35 

59 

15 

23 

5 

94 

34.44 

58 

14.44 

22 

5.55 

93 

33.89 

57 

13.89 

21 

6.11 

92 

33.33 

56 

13.33 

20 

6.67 

91 

32.78 

55 

12.78 

19 

7.22 

90 

32  22 

54 

12.22 

18 

7.78 

89 

31.67 

53 

11.67 

17 

8.33 

88 

31.11 

52 

11.11 

16 

8.89 

87 

30.55 

51 

10.55 

15 

9.44 

86 

30 

50 

10 

14 

10 

85 

29.44 

49 

9.44 

13 

10.55 

84 

28.89 

48 

8.89 

12 

11.11 

83 

28.33 

47 

8.33 

11 

11.67 

82 

27.78 

46 

7.78 

10 

12.22 

81 

27.22 

45 

7.22 

9 

12.78 

80 

26.67 

44 

6.67 

8 

13.33 

79 

26.11 

43 

6.11 

7 

13.89 

78 

25.55 

42 

5.55 

6 

14.44 

77 

25 

41 

5 

5 

15.00 

76 

24.44 

40 

4.44 

4 

15.55 

75 

23.89 

39 

3.89 

3 

16.11 

74 

23.33 

38 

3.33 

2 

16.67 

73 

22.78 

37 

2.78 

1 

17.22 

72 

22.22 

36 

2.22 

0 

17.78 

71 

21.67 

35 

1.67 

—1 

18.33 

70 

21.11 

34 

1.11 

2 

18.89 

69 

20.55 

33 

0.55 

3 

19.44 

To  convert  deg.  Fahrenheit  to  corresponding  deg.  Centigrade: 
Subtract  32,  multiply  difference  by  5,  and  divide  by  9. 
Example:    Which  degree  Centigrade  corresponds  to  110°  F.?    110  -  32  = 

78;  78  X  5  =  390;  390  +  9  =  43.33. 

To  convert  deg.  Centigrade  to  corresponding  deg.  Fahrenheit: 
Multiply  by  9,  divide  product  by  5,  and  add  32  to  quotient. 
Example:    Which  degree  Fahrenheit  corresponds  to  96.6°  C?    95.6  X  9  = 

859.5;  859.5  -i-  5  =  171.9;  171.9  +  32  =  20.'?.fi. 


Appendioc. 


259 


Table  XV.     Comparison  of  metric  and  customary  weights  and 

measures. 


Customary 

wei.i?hts  and 

measures. 


1  inch 

Ifoot 

1  mile 

1  square  inch.. 
1  squiire  foot .. 
1  square  yard. 

1  acre 

1  cubic  inch... 
1  cubic  foot.... 
1  cubic  yard... 

1  bushel 

1  fluid  ounce.. 

1  quart 

1  gallon 

1  grain 

1  ounce  (av.).. 
1  pound  (av. ) 


Equivalents  in 
metric  system. 


2.54  centimeters. 
.3048  meter. 
1.6094  kilometers. 
6.452  sq.  centimeters. 
9.29  sq.  decimeters. 
.886  sq.  meter. 
.4047  hectare. 
16.387  cc. 
.0283  cub.  meter. 
.765  cub.  meter. 
.3552  hectoliter. 
29.57  cc. 
.9464  liter. 
3.7854  liters. 
64.8  milligrams. 
28.35  grams. 
.4536  kilogram. 


Metric  weigtits 

and 

measures. 


1  meter 

1  meter 

1  kilometer 

1  sq.  centimeter 
1  square  meter.. 
1  square  meter.. 

1  hectare  

1  cc 

1  cub.  decimeter 

1  cub.  meter 

1  hectoliter 

Ice 

inter 

1  decaliter 

1  gram 

1  gram 

1  kilogram 


Equivalents  in 
customary  system. 


.37  inches. 
.0936  yards. 
.6214  mile. 
.155  sq.  inch. 
.  764  sq.  feet. 
.196  sq.  yards. 
.471  acres. 
.061  cubic  inch. 
.023  cubic  inches. 
.314  cub.  feet. 
.8377  bushels. 
.0338  fluid  ounce. 
.0567  quarts. 
.6417  quarts. 
.43  grains. 
.035274  ounce. 
.  2046  pounds (av. 


2 GO  Testing  Milk  and  Its  Products. 

SL'GGCSIIONS  regarding    the  orgsnization  of  co-operative 
creameries    and  cheese    factories. 

When  the  fanners  of  a  neighborhood  are  considering  the 
establishment  of  a  creamery  or  cheese  factory,  they  should  first 
of  all  make  an  accurate  canvas  of  the  locality  to  ascertain  the 
lUJi-iber  of  cows  that  can  be  depended  on  to  supply  the  factory 
with  milk.  The  area  which  may  be  drawn  from  will  vary 
according  to  the  kind  of  factory  which  it  is  desired  to  ox^crale. 
A  successful  separator  creamery  will  need  at  least  400  cows 
witiiin  a  radius  of  four  to  five  miles  from  the  proposed  factory.' 
Suiall  cheese  factories  can  be  operated  with  less  milk,  and 
gathered-cream  and  butter  factories  generally  cover  a  much 
larger  territory  than  that  mentioned.  In  all  cases,  however, 
the  question  of  the  number  Of  cows  contributing  to  the  enter- 
prise must  be  fully  settled  before  further  steps  are  taken,  since 
this  is  a  point  upon  which  success  will  largely  depend. 

Methods  of  organization.  The  farmers  should  form  their  own 
organization,  and  not  accept  articles  of  agreement  proposed  by 
traveling  agents.  An  agreement  to  supply  milk  from  a  stated 
number  of  cows  should  be  signed  by  all  expecting  to  join  the 
association.  When  a  sufficient  numl^er  of  cows  has  been 
pledged  to  insure  the  successful  operation  of  a  factor}^  the  fann- 
ers agreeing  to  supply  milk  should  meet  and  form  au  organi- 
zation. This  may  be  done  according  to  either  of  the  following 
plans  which  have  been  known  to  give  good  satisfaction. 

Raising  money  for  building  and  equipment. 

First. — Each  member  will  sign  an  agreement  to  pay  on  or 
before  a  given  date  for  a  certain  number  of  shares  in  the  com- 
pany at dollars  per  share;  or, 

Second. — An  elected  board  of  directors  may  be  authorized  to 

borrow  a  sum  of  money  not  exceeding thousand  dollars 

on  their  individual  responsibility,  and  the  sum  of cents, 

(usually  five  cents)  per  hundred  pounds  of  milk  received  at 
the  factory  shall  be  reserved  for  the  payment  of  this  borrowed 
money. 

1  Bull.  56,  Wisconsin  experiment  station. 


Appendix.  261 

Constitution  and  by-laws  of  a  co-operative  association  are  drawn 
up  and  signed  by  the  prospective  niembei*s  of  the  association 
when  it  has  been  determined  to  form  such  an  association.  It 
is  impossible  to  include  in  an  illustration  all  the  articles  and 
rules  that  may  be  found  useful  in  each  particular  instance;  the 
following  suggestions  in  regard  to  some  of  the  points  to  be  in- 
cluded in  the  documents  are  given  as  a  guide  only.  It  may  be 
found  advisable  to  modify  them  in  various  ways  to  meet  the 
needs  of  the  organization  to  be  formed. 

After  the  constitution  and  by-laws  have  been  drawn  up  and 
made  plain  to  all  the  members  of  the  association,  they  should 
be  printed  and  copies  distributed  to  all  parties  interested. 

Constitution 

OR 

Articles   of   Agreement   of   the Association.^ 

1.  The  undersigned,  residents  within  the  Counties  of , 

State  of ,  hereby  agree  to  become  members  of  the 

Co-operative  Association,  which  is  formed  for  the  purpose  of 
manufacturing  butter  or  cheese  from  whole  milk. 

2.  The  regular  meetings  of  the  association  shall  be  held  an- 
nually on  the day  of  the  month  of Special 

meetings  may  be  called  by  the  president,  or  on  written  request 
of  ojie-third  of  the  members  of  the  association,  provided  three 
day's  notice  of  such  meeting  is  sent  to  all  members. 

Meetings  of  the  board  of  directors  may  be  called  in  the  same 
way,  either  by  the  president  or  by  any  two  members  of  the 
board  of  directors. 

3.  Ten  members  of  the  association,  or  three  of  the  board  of 
directors,  shall  constitute  a  quorum  for  the  transaction  of  busi- 
ness. 

4.  The  officers  of  the  association  shall  include  president,  sec- 
retary, treasurer,  one  of  whom  is  also  elected  manager,  and 
these  officers  together  with  three  other  members  of  the  associa- 


iThe  following  publications  have  been  freely  used  In  preparing  this 
constitution  and  by-laws:  Woll,  Handbook  f.  Farmers  and  Dairymen; 
Minn,  experiment  station,  bull.  No.  35;  Ontario  Agriculture  College,  spec- 
ial bulletin,  May  1897. 


202  Testing  Milk  and  Its  Products. 

tion  shall  constitute  the  board  of  directors.  Each  of  these  six 
officers  shall  be  elected  at  the  annual  meeting  and  hold  office 
for  one  year,  or  until  their  successors  have  been  elected  and 
qualified.  Any  vacancies  in  the  board  of  directors  may  be  filled 
by  the  directors  until  the  next  annual  meeting  of  the  association. 

5.  The  duties  of  the  president  shall  be  to  preside  at  all  meet- 
ings of  the  association,  and  perform  the  usual  duties  of  such 
presiding  officers.  He  shall  sign  all  drafts  and  documents  of 
any  kind  relating  to  the  business  of  the  association,  and  pay 
all  money  which  comes  into  his  possession  by  virtue  of  his 
office,  to  the  treasurer,  taking  his  receipt  therefor.  He  shall 
call  special  meetings  of  the  association  when  deemed  necessary. 

In  the  absence  of  the  president,  one  of  the  board  of  directors 
shall  temporarily  fill  the  position. 

6.  The  secretary  shall  attend  all  business  meetings  of  the 
association  and  of  the  board  of  directors  and  shall  keep  a  care- 
ful record  of  the  minutes  of  the  meetings.  He  shall  also  give 
notices  of  all  meetings  and  all  appointments  on  committees, 
etc.  He  shall  sign  all  papers  issued,  conduct  the  correspond- 
ence and  general  business  of  the  association,  and  keep  a  correct 
financial  account  between  the  association  and  its  members.  He 
shall  have  charge  of  all  property  of  the  association  not  other- 
wise disposed  of,  give  bonds  for  the  faithful  performance  of  his 
duties,  and  receive  such  compensation  for  his  services  as  the 
board  of  directors  may  determine. 

7.  The  treasurer  shall  receive  and  give  receipt  for  all  money 
belonging  to  the  association,  and  pay  out  the  same  upon  ordei*s 
signed  by  the  president  and  the  secretary.  He  shall  give  such 
bonds  as  the  board  of  directors  may  require. 

8.  The  board  of  directors  shall  audit  the  accounts  of  the 
association,  invest  its  funds,  appoint  agents,  and  deterniiue  all 
compensations.  They  shall  prescribe  and  enforce  the  rules  and 
regulations  of  the  factory.  They  shall  cause  to  be  kept  a  rec- 
ord of  the  weights  and  tests  of  the  milk  or  cream  received  from 
each  patron,  the  products  sold,  the  running  expenses,  etc.,  and 
si  all  divide  among  the  patrons  the  money  due  them  each 
month.    They  shall  also  make  some  provision  for  the  with- 


Appendix.  2  33 

drawal  of  any  member  from  the  association,  and  make  a  report 
in  detail  to  the  association  at  the  annual  meeting.  Such  report 
shall  include  the  gross  amount  of  milk  handled  during  the 
year,  the  receipts  from  products  sold,  and  all  other  receipts,  the 
amounts  paid  for  milk  and  for  running  expenses,  and  a  com- 
plete statement  of  all  other  matters  pertaining  to  the  business 
of  the  association. 

9.  Among  the  rules  and  regulations  to  be  enforced  by  the 
board  of  directors  may  be  included  some  or  all  of  the  following: 

a.  Patrons  shall  furnish  all  the  milk  from  all  the  cows  prom- 
ised at  organization  of  the  association. 

b.  Only  sweet  and  pure  milk  will  be  accepted  at  the  factory, 
and  any  tainted  or  sour  milk  shall  be  refused. 

c.  The  milk  of  each  patron  shall  be  tested  at  least  three  times 
a  month. 

d.  Any  patron  proved  to  be  guilty  of  watering,  skimming  or 
otherwise  adulterating  the  milk  sent  to  the  factory,  or  by  tak- 
ing more  than  80  pounds  of  skim  milk  or  whey  for  every  100 
pounds  of  whole  milk  delivered  to  the  factory,  shall  be  fined  as 
agreed  by  the  association. 

e.  A  partron's  premises  may  be  inspected  at  any  time  by  the 
board  of  directors,  or  their  authorized  agent,  for  the  purpose  of 
suggesting  improvements  in  the  methods  of  caring  for  the  milk 
or  the  cows,  in  drainage  and  general  cleanliness;  or  to  secure 
samples  of  the  milk  of  his  cows  for  examination  when  it  is 
deemed  necessary. 

10.  Any  changes  or  amendments  to  the  by-laws  or  constitu- 
tion of  the  association  must  be  made  in  writing  by  the  parties 
proposing  the  same,  and  posted  prominently  in  a  conspicuous 
place  at  the  creamery,  at  least  two  weeks  previous  to  their  being 
acted  upon.  Such  changes  to  be  in  force  must  be  adopted  by  a 
two-thirds  vote  of  the  stockholders. 

11.  In  voting  at  any  annual  or  special  meeting  of  the  asso- 
ciation, the  members  shall  be  entitled  to  one  vote  for  each  cow 
supplying  milk  to  the  factory,  or  for  each  share  of  the  stock 
owned  by  them,  as  agreed  upon. 


INDEX. 


The  figures  refer  to  pages  in  the  book. 


Acid   measures,    33,    46,    53. 

Acid  tester,   Swedish,   66. 

Acidity  of  cream,  118;  estima- 
tion  of,    123. 

Acidity  of  milk,  cause  of,  108; 
determination  of,  109,  213; 
methods   of  testing,   120. 

Accuracy  of  alkaline  tablets, 
117. 

Adulteration  of  milk,  101,  106, 
224;    calculation   of,    106. 

Adulterated  butter,  219;  cheese, 
223. 

Albumen,  15;  determination  of, 
in    milk,209,    211. 

Albuminoids,   15. 

Albumose,    16. 

Alkaline  tablet  test,  113:  stand- 
ard solution  of,  116;  accu- 
racy, 117. 

Alkaline    tabs,     124. 

American    Cheddar    cheese,     22. 

Amphoteric  reaction  of  milk, 
108. 

Analysis,  chemical,  of  butter, 
216,  217;  butter  milk,  213; 
cheese,  222;  condensed  milk, 
215;  cream,  213;  milk,  204; 
skim     milk,     213;     whey,     213. 

Appendix,   233. 

Artificial  butter,  detection  of, 
219. 

Ash,  determination  of,  in  but- 
ter, 217,  218;  in  cheese,  223;  in 
milk,   17,    212. 


Babcock  test,  the,  6,  28;  Bart- 
lett's  modification  of,  71; 
direction  for,  29;  discussion  of 
details,  37;  for  butter  milk, 
89;  for  cheese,  89;  for  con- 
densed milk,  90;  for  cream, 
74,  169;  for  skim  milk,  85;  for 
whey,  89;  glassware  used  in, 
38;  modifications  of,  70; 
scales  for  weighing  cream, 
cheese,  etc.,  82;  water  to  be 
used  in,   69. 


Bartlett's  modification  of  Bab- 
cock test,  71. 

Bausch  and  Lomb  centrifuge, 
72. 

Beimling  test,   5. 

Bi-carbonate  of  soda,  detection 
of,   in  milk,   229. 

Bi-chromate  of  potash,  98,  156; 
solution  of,  99. 

Board  of  health  "degi'ees,  97,  236. 

Boiled  milk,  detection  of,   227. 

Boiling   test,    the,    221. 

Boracic  acid,  in  dairy  products, 
124,    228. 

Borax  in  dairy   products,    228. 

B.SzW.    bottle,     87. 

Butter,  artificial,  13;  detection 
of,    219. 

Butter  chart,   253;  use  of,  185. 

Butter,  20;  chemical  analysis 
of,  216;  complete  analysis 
in  same  sample,  217;  com- 
position of,  21,  233;  defini- 
tion, 232;  determination  of 
ash,  217;  casein,  216;  fat,  216; 
water,  216;  renovated,  222; 
sampling  for  analysis,  216; 
standard,  232;  variations  in 
composition,  177;  yield,  cal- 
culation of,   176. 

Butter  fat,  conversion  factor 
for,  183;  definition,  232;  de- 
termination of  specific  grav- 
ity, 220;  volatile  fatty  acids, 
220;  expansion  co-efficient, 
36;  price  per  pound,  190; 
specific  gravity,  38;  standard, 
231;  table  showing  amounts 
due  for,  at  12  to  25  cents  per 
pound,  247;  test  and  yield  of 
butter,    176. 

Butter  making,  quantities  of 
products  obtained  in,  21. 

Butter  milk,  21;  Babcock  test 
for,  89;  chemical  analysis  of, 
213;  composition  of,  233;  spe- 
cific  gravity  of,    214. 


Index. 


265 


Calculation  of  adulteration,  106; 
of  concentration  of  condensed 
milk,  215;  of  milk  solids,  99, 
100;  of  over-run,  183;  of  sp. 
gr.  of  milk  solids,  103;  of 
yield  of  butter,  176,  182,  184; 
of  cheese,  187;  of  dividends 
at  creameries,  190;  at  cheese 
factories,  l\)i)',  of  percentages, 
159. 

Calibration  of  glassware,   47. 

Carbohydrates,    16. 

Casein,  14;  determination  of,  in 
butter,  216;  in  cheese,  223;  in 
milk,   209,   211. 

Centrifugal  machines,   54. 

Chamberland  filters,  15. 

Cheddar  cheese,  American,  22; 
composition,   233. 

Cheese,  22;  Babcock  test  for, 
89;  calculating  yield  of,  from 
casein  and  fat,  189;  from  fat, 
187;  from  solids  not  fat  and 
fat,  188;  composition,  233; 
chemical  analysis  of,  222; 
definitions,  232;  determina- 
tion of  ash,  '^^6;  casein,  223; 
fat,  222;  water,  222;  "filled," 
detection  of,  223;  quality  of, 
from  milk  of  different  rich- 
ness, 200;  sampling,  89; 
standard,  232;  yield,  calcula- 
tion of,  187;  yield  of,  and 
quality  of  milk,  relation  be- 
tween, 188. 

Cheese  factories,  calculating 
dividends  at,  199;  co-opera- 
tive,   202;    proprietary,    202. 

Cholesterin  in  milk,  19. 

Citric  acid  in  milk,  19. 

Cleaning  solutions  for  test  bot- 
tles,  44. 

Cleaning  test  bottles,  40;  ap- 
paratus for,  41. 

Cochran's  test,  5. 

Coloring  matter  in  milk,  for- 
eign,  detection  of,    226. 

Colostrum  milk,  19;  composi- 
tion  of,    233. 

18 


Composite  samples,  148.;  care 
of,  158;  case  for  holding,  154; 
methods  of  taking,  148;  pre- 
servatives for,  155. 

Composite  sampling,  accuracy 
of,  155;  use  of  drip  sample, 
150;  one-third  sample  pip- 
ette, 153;  Scovell  sampling 
tube,  151;  tin  dipper,  148; 
equity  milk   sampler,    153. 

Composition  of  butter,  233;  but- 
ter milk,  233;  cheese,  233; 
colostrum  milk,  233;  con- 
densed milk,  233;  cream,  233; 
milk,  19,  233;  milk  ash,  18; 
skim    milk,    233;    whey,    233. 

Condensed  milk,  22;  analysis 
of,  215;  composition  of,  233; 
determination  of  concentra- 
tion, 216;  of  sp.  gr.  of,  215; 
testing    of,    90,    91. 

Control  sample  of  milk,  101. 

Conversion  factor  for  butter 
fat,   183. 

Conversion  tables  for  thermo- 
meter scales,  257;  for  weights 
and  measures,  258. 

Cows,  number  of  tests  required 
in  testing,  136;  when  to  test, 
138. 

Cows'  milk,  composition  of,  19, 
233. 

Cream,  20;  acidity  of,  120;  Bab- 
cock test  for,  73,  169;  bottles, 
the  bulb-necked,  76;  the  Win- 
ton,  77;  care  In  sampling,  ne- 
necessity  of  171;  definition, 
232;  determinaiion  of  acidity 
of,  114,  123;  errors  of  mea- 
suring in  testing.  74;  evapo- 
rated, 232;  gelatin  in,  detec- 
tion of,  227;  pasteurized,  de- 
tection of,  226*  scales,  78; 
separator,  20;  separation  of, 
infiuence  of  temperature,  174; 
spaces,  165;  specific  gravity, 
75;  standard,  232;  starch  In, 
228;  testing,  73;  testing  outfit, 
170;  testing  at  creameries, 
165;    use    of    5    cc,    pipette    in, 


266 


Testing  Milk  and  It$  Products. 


82;  use  of  milk  test  bottles 
in,  81;  test  bottles,  76;  weight 
of,  delivered  by  a  17.6  cc. 
pipette,   75. 

Creameries,  calculating  divi- 
dends at,  190,  192;  co-opera- 
tive, 191;  cream  testing  at, 
165;  proprietary,  191. 

Creamery  inch,   1,   167. 

Curd  test,  the  Wisconsin  im- 
proved,  125. 

Definitions  of  milk  and  its 
products,   231. 

DeLaval's   butyrometer,    8. 

Devarda's   acidimeter,    113. 

Diameter  of  tester  and  speed 
required,  relation  between,  57. 

Dividends,  calculating,  at  cheese 
factories,  199;  at  creameries, 
190;  of  both  milk  and  cream 
at   the   same   factory,    198. 

Dividers,    Lutley,   37. 

Double-necked  test  bottles,  87; 
value  of  divisions  of,  87. 

Draining  rack  for  test  bot- 
tles,  43. 

Equity  milk  sampler,   153. 
Expansion  coefficient  for  butter 
fat,   36. 

Failyer  and   Willard's   test,    5. 

Farrington's  alkaline  tablet 
test,   113. 

Fat,  12;  color  of,  an  index  to 
strengtn  of  acid  used,  66; 
content,  causes  of  variation 
in,  135;  determination  of,  in 
butter,  216;  in  cheese,  222; 
in  milk,  208;  globules,  12;  in- 
fluence of  temperature  on 
separation  of,  67;  measuring 
of,  in  cream  testing,  83;  in 
milk  testing,  35;  pounds  in 
1-10,000  lbs.  of  milk,  testing  3 
to  5.35  per  cent.,  241;  speed 
required  for  complete  sepa- 
ration of,  56. 

Fermentation   test,    the,    128. 

Filled  cheese,   detection  of,   223. 


"Fitch's    Salt    Analysis,"    218. 
Fjord's    centrifugal    cream    test, 

9. 
Fluorids,    detection   of,    in    nilk, 

230. 
Food,    influence    of.    on    quality 

of  milk,   143,  145. 
Food      standards.      Government, 

231. 
Fool  pipettes,  45. 
Formaldehyd,     detection    of,     in 

milk,    230. 
Frozen  milk,   sampling  of,    27. 

Gauges  of  cream,   165. 

Gelatine  in  cream,   detection  of, 

227. 
Gerber's     acid -butyrometer,      7; 

fermentation  test,  128. 
Glassware   used  in   the  Babcock 

test,   38;   calibration  of,   47. 
Globulin,   15. 

Glycerides  of  fatty  acids,  13. 
Goat  cheese,   14. 
Government       food      standards, 

231. 
Grain-feeding,    heavy,    influence 

of,  on  qualitj'  of  milk,  143. 
Gurler's       method      of      testing 

cows,  138. 

Hand  testers,   59. 

Hemi-albumose,    15. 

Herd    milk,    variations    in,    142; 

ranges   in   variation   of,    143. 
iiypoxanthin     19. 

Introduction,    1. 
Iowa  station  test,  5. 

Kumiss,   231. 

Lactic  acid  in  milk,   16. 

Lactocrite,  5,  8. 

Lactose,  16. 

Lactochrome,   19. 

Lactometer,  the,  and  its  appli- 
cation, 93;  bi-chromate,  in- 
fluence on,  98;  cleaning  of,  99; 
degrees,  94;  N.  Y.  board  of 
health,  96,  236;  Quevenne,  93; 
reading  the,  97;  time  of  tak- 
ing readings,  98. 


Index. 


267 


Lecithin  in  milk,   19. 
Tjeffmann  and  Beam   test,   5. 
Legal    standards    for    milk,    102, 

235. 
Liebermann's  method,  5. 
Lutley  dividers,   37. 

Manns'  test,  110. 

Marschall  rennet  test,  130. 

Measuring  fat  column  in  test- 
ing cream,  83;  in  testing  milk, 
35. 

Mercury,  calibration  with,  47; 
cleaning,  48. 

Metric  and  customary  systems 
of  weights  and  measures, 
comparison  of,  259. 

Milk,  acidity  of,  108;  adultera- 
tion of,  101;  amphoteric  re- 
action of,  108;  ash,  composi- 
tion of,  19;  boiled,  detection 
of,  227;  chemical  analysis  of, 
204;  cholesterin  in,  19;  citric 
acid  in,  19;  colostrum,  19; 
composition  of,  11;  table 
showing  composition  of,  233; 
composite  sampling  of,  148; 
condensed,  22,  90,  233;  correc- 
tion taoie  for  specific  grav- 
ity, 237;  definitions,  231;  de- 
tection of  preservatives  in, 
124,  2:^s;  determmation  of 
acidity,  120,  213;  of  ash,  212; 
of  casein  and  albumen.  209, 
211;  of  fat,  208;  of  milk  sugar, 
212;  of  specific  gravity,  204; 
of  water,  207.  208;  fat  avail- 
able for  butter  in  different 
grades  of,  i82;  from  cows  in 
heat,  102;  from  sick  cows, 
102;  from  single  cows,  sam- 
pling of,  139;  variations  in, 
131;  frozen,  sampling  of,  27; 
gases,  19;  hypoxanthin,  19; 
lactochrome,  19;  lecithni,  19; 
legal  standards,  102,  234;  mi- 
croscopic impurities,  228; 
mineral  components,  18;  par- 
tially churned,  sampling  of, 
24;  quality  of,  influence  of 
food,      145;      of     heavy     grain 


feeding,  143;  of  pasture,  145; 
method  of  improving,  146; 
sampling,  26;  scales,  139; 
serum,  11;  skimming,  156; 
solids,  11;  calculation  of,  99; 
specific  gravity  of,  103;  sour- 
ing of,  16;  sour,  sampling  of, 
25;  standards,  102,  231,  234; 
sugar,  16;  testing  purity  of, 
125;  urea,  19;  water,  12; 
watering  of,  106;  watering 
and  skimming,   106. 

Milk  test,  a  practical,  need  of, 
1;  requirements  of,  6;  bottle, 
use  of,  in  testing  cream,  81; 
Russian,    70. 

Milk  tests,  Beimling  (Leff- 
mann  and  Beam)  5;  Cochran, 
5;  DeLaval  butyrometer,  8; 
Failyer  and  Willard,  5;  Fjord, 
9;  foreign,  7;  Gerber  acid- 
butyrometer,  7;  introduction 
of,  4;  lactocrite,  5,  8;  Lieber- 
mann,  5;  Nahm,  5;  Parson,  5; 
Patrick  (Iowa  station  test), 
5;  reiractometer,  10;  Rose- 
Gottlieb,  5;  Schmied,  5;  Short, 
4;  Thorner,  5. 

Milk  products,  composition  of, 
19,    233. 

Monrad  rennet  test,    the,    129. 

Milk  testing,  29;  on  the  farm, 
131. 


N.  Y.  board  of  health  lacto- 
meter, 96;  degrees  correspond- 
ing to  Quevenne  lactometer 
degrees,   236. 

Nafis  modification,  of  test  bot- 
tle calibrator,  52. 

Nitric  acid  test  for  adulteration 
of  milk,   224. 

Non-fatty  milk  solids,   11. 

Normal  solutions,   110. 

Nuclein,  15. 

Oil-test  churn,   2,   166. 
Ohlsson  test  bottle,  87. 
Oleomargarine,      detection      of, 
219;   cheese,   detection  of,   223. 


268 


Testing  Milk  and  Its  Products. 


One-third  sampling  pipette,  use 
of,  153. 

Organization  of  co-operative 
creameries  and  clieese  fac- 
tories, suggestions  concern- 
ing,  260. 

Overrun,  179;  calculation  of, 
183;  factors  influencing,  179; 
table,  186,  255. 

Parson's  test,  5. 

Pasteurized  milk  or  cream,  de- 
tection of,   226. 

Pasture,  influence  of,  on  quality 
of  milk,   145. 

Patrick's  test,  5. 

Patron's   dilemma,   a,    162. 

Percentages,  average,  methods 
of  calculation,  160;  fallacy  of 
averaging,   159. 

Phenolphtalein,   111. 

Physician's  centrifuge,  u.se  of, 
in  milk  testing,   73. 

Pipettes,  44,  53;  proper  con- 
struction of  points,  4&;  pro- 
per method  of  emptying,  31; 
calibration,   53. 

Potassium    bl-chromate,    156. 

Power  testers,  61. 

Preservaline,  124,  220;  detec- 
tion of,  in  milk,  124. 

Preservatives,  for  composite 
samples,  156;  in  milk,  detec- 
tion of,  124,   220. 

Primost,  14. 

Process  butter,  detection  of, 
222. 

Proteose,  15. 

Quevenne  lactometer,  the,  93; 
degrees  corresponding  to 
scale  of  N.  Y.  board  of  health 
lactometer,   96,   236. 

Recknagel's  phenomenon,   98. 
Refractometer,  10. 
Reichert  number,  221. 
Reichert-WoUny    method,    220. 
Relative-value    tables,    196,    249. 
Rennet  tests,   129. 


Renovated  butter  tests,  for  de- 
tection of,  221;  boiling  test. 
221;    Waterhouse   test,    221. 

Reservoir  for  water  in  Babcock 
test,  71. 

Rose-Gottlieb   method,   5. 

Russian  milk  test,  the.  70. 


Salicylic  acid,  in  milk,  detec- 
tion of,  230. 

Sait,    estimation   in   butter,    218. 

Sampling  cheese,  89;  milk,  23. 
29;  milk  from  single  cows, 
139. 

Sampling  tube,  for  cream,  171; 
Scovell,    151;   equity,   153. 

Scales  for  weighing  cream,  78; 
milk,   139. 

Schmied  method,  the,  5. 

Scovell  sampling  tube,   151. 

Serum  solids,  11. 

Short's  test,   4. 

Siegfeld's  modiflcation  of  Bab- 
cock's  test,  73. 

Sinking  fund,  195. 

Separator  cream,  20. 

Skimming  of  milk,  detection  of, 
106. 

Skim  milk,  20;  Babcock  test 
for,  85;  chemical  analysis  of, 
213;  composition  of,  233;  test 
bottles,  87,  88.  » 

Solids  not  fat,  11;  formulas  for 
calculating,  100;  tables  show- 
ing, corresponding  to  0-6  per 
cent,  fat  and  26-36  lactometer 
degrees,  238. 

Sour  milk,  sampling  of,  26. 

Space  system,  the,  165. 

Specific  gravity,  93:  cylinders, 
94,  97;  influence  of  tempera- 
ture, 95;  of  butter  fat,  deter- 
mination of,  220;  of  butter 
milk,  214;  of  condensed  milk, 
215;  of  milk,  204,  206;  of  milk 
solids,  103;  of  sour  milk,  214; 
temperature  correction  table, 
237. 

Speed  required  for  complete 
separation  of  fat,  55. 


Index. 


269 


Spillman's   cylinder,    120. 

Standard  measure  for  calibrat- 
ing test  bottles,  52. 

Standards  of  purity,  Govern- 
ment, for  milk  and  its  prod- 
ucts,   231. 

Starch   in   cream,    228. 

Steam  turbine  testers,  61,  62. 

Sulfuric  acid,  63;  table  showing 
strength  of,  65;  testing 
strength  of,   64. 

Sweetened    condensed    milk,    91. 

Swedish  acid  bottle,  46. 

Swedish  acid  tester,  66. 

Tank  for  cleaning  test  bottles, 
43. 

Temperature  of  turbine  testers, 
62;  of  fat  when  tests  are  read. 
36. 

Test  bottles,  31,  38;  apparatus 
for  cleaning,  42:  bulb-necked 
cream,  78;  calibration,  53; 
cleaning,  40;  cream,  78; 
double-necked,  87;  draining- 
rack  for,  41;  marking,  39;  for 
cream  testing,  78;  for  skim 
milk  testing.  87;  rack  for  use 
in  creameries  and  cheese  fac- 
tories, 154;  tank  for  cleaning, 
43,  Winton  cream,   79. 

Testers,  54;  ascertaining  speed 
of,  58;  hand,  59;  power,  61. 

Testing  cows,  number  of  tests 
required  during  a  period  of 
lactation,    136. 

Testing  milk  and  its  products, 
1;  on  the  farm,  131. 

Test  sample,  size  of,  142. 

Thermometer  scales,  compari- 
son of,  257. 

Thermometer  in  frame  of  tur- 
bine testers,    63. 

Thorner's  method,   5. 

Total  solids  in  milk,  11;  deter- 
mination of,  208. 

Trowbridge  method  of  calibra- 
tion, 50. 

Turbine  testers,  61,  62. 

Variation     in     composition     of 


Variation  in  quality  of  milk, 
131,  143;  causes  of,  135;  lati- 
tude of,  102;  ranges  in,  143. 

Volatile  acids,  220. 

Wagner  skim  milk  bottle,   88. 

Waste  acid  jar,  41. 

Water,  calibration  with,  49;  de- 
termination of,  in  butter,  216; 
in  cheese,  2z^;  in  milk,  207, 
208;  oil-stove  for  heating,  34; 
reservoir  for,  69;  to  be  used 
in  tne  Babcock  test,  68. 

Waterhouse  test,   221. 

Watering  of  milk,  detection  of, 
106. 

Watering  and  skimming  of 
milk,  aetection  of,   106. 

Weights  and  measures,  compar- 
ison of  metric  and  customary, 
257. 

Westphal  balance,  206. 

Whey,  22;  Babcock  test  for,  89; 
chemical  analysis  of,  213; 
composition  of,  233;  defini- 
tion, 232. 

Winton  cream  bottle,   the,   79. 

Wisconsin  creamery  butter, 
summary   of   analyses,    178. 

Wisconsin  curd  test,  the  im- 
proved,  125. 

Wollny's    refractometer,    10. 

World's  Fair  breed  tests,  com- 
position of  butter  from,  177; 
variation  in  quality  of  milk, 
142. 

Yield  of  butter,  calculation  of, 
176;  and  butter  fat  test,  176; 
trom  milk  of  different  rich- 
ness, 182;  table  showing, 
from  1  to  10,000  lbs.  of  milk, 
testing  3  to  5.35  per  cent.,  253. 

Yield  of  cheese,  calculation  of, 
187;  relation  between,  and 
quality  of  milk,  187;  table 
showing,  corresponding  to 
2.5  to  6  per  cent,  of  fat,  with 
lactometer  readings  of  26  to 
36,   256. 


butter,   177. 


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only  one.  You'll  find  you've 
got  a  bucket  bowl  if  you  buy 
any  other— for  all  others 
have  bucket  bowls. 

Here's  something  simple  — 
just  a  light  Tubular  Bowl  — 
with  only  one  plain  little 
piece  inside.  The  piece 
comes  out  —  the  bowl  is 
washed  —  the  piece  is  put 
back  —  all  in  three  minutes. 

Here's  something  more  —  a  low  supply  can  —  hardly 
waist  high.     A  child  can  see  into  it  —  fill  it  —  easily. 

Here's  another  thing  —  entirely  enclosed  gears,  run- 
ning in  a  mist  of  oil.  No  accidents,  no  oil  cups  to 
fill,  no  oil  holes  to  dig  out  with  a  pin. 

Guess  you  see  the  diflference  between  Tubulars  and 
the  bucket  bowl  kind.  Our  handsome  catalog  tells  all 
about  it — it  is  free  for  the  asking.   May  we  send  you  one? 


The  Sharpies  Co., 

Chicago,  ill. 


P.  M.  Sharpies, 
West  Chester,  Pa. 


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